Download TOPIC 1 Work with numbers

TOPIC 1
Work with numbers
By the end of this topic, you should be able to:
ü Identify the number of significant figures in a number
ü Round numbers to a given number of decimal places or a given
number of significant figures
ü Approximate computations that involve sums, differences, products
and quotients to a specified place value, decimal place or number of
significant figures
ü Solve mathematical puzzles
ü Complete a number sequence that involves a mixture of whole
numbers, directed numbers, fractions, decimals and percentages.
Discuss approximation and estimation
Oral activity
1 Describe “approximation” and “estimation”.
2 Discuss with your partner what you remember about
approximation and estimation from Form 1.
3 Name some examples in which we use approximation
and estimation.
4 Look at the road map of Botswana below. Discuss how you
use the scale to estimate distances on the map.
Chobe
N.P.
Sepupa
Nxainxai
Maun
Tsau
Sehithwa
Nxai Pan
N.P.
Gweta
Nata
Mosetse
Francistown
Ghanzi
Kalkfontein
Orapa
Serule
Mamuno
Serowe
SelebiPhikwe
Mahalapye
Stockpoort
Kang
Hukuntsi
Tshane
Jwaneng
Molepolole
Kanye
Mochudi
GABORONE
N
Ramotswa
Lobatse
Tshabong
180 km
Map of Botswana showing major roads
2
PAIR
TOPIC 1 Work with numbers
Approximation
Key concept
An approximation of a number or measurement is a value that is
close to, but not equal to, the actual value. We use approximations to
help us estimate the answers of computations. For example, we can
use rounding to find the approximate values of numbers.
Approximate answers
of computations.
The following are three methods we can use to round numbers.
1 Round to the nearest 10, 100, 1 000 and so on.
2 Round to a given number of decimal places.
3 Round to a given number of significant figures.
1 Round to the nearest 10, 100 or 1 000
To round to the nearest 10, look at the last digit in the number.
The last digit in a whole number is the units’ digit. If the last digit
is less than 5, round down to the lower 10. If the last digit is 5 or
more, round up to the higher 10. For example, 326 rounded to the
nearest 10 is 330 and 152 rounded to the nearest 10 is 150.
To round to the nearest 100, look at the last two digits in the number.
The second last digit in a whole number is the tens’ digit. If the
last two digits are less then 50, round down to the lower 100. If
the last two digits are 50 or more, round up to the higher 100. For
example, 445 rounded to the nearest 100 is 400, 563 rounded to the
nearest 100 is 600 and 221 rounded to the nearest 100 is 200.
To round to the nearest 1 000, look at the last three digits in the
number. The third last digit in a whole number is the hundreds’
digit. If the last three digits are less than 500, round down to the
lower 1 000. If the last three digits are 500 or more, round up to
the higher 1 000. For example, 2 780 rounded to the nearest 1 000
is 3 000 and 2 430 rounded to the nearest 1 000 is 2 000.
Example 1
The highest point of Lentswe La Baratani at Otse is 1 491 m above
sea level.
1 Round this height correct to the nearest 10 m.
2 Round this height correct to the nearest 100 m.
3 Round this height correct to the nearest 1 000 m.
Note
Lentswe La Baratani is
15 km from Lobatse.
Solutions
1 1 490 m
2 1 500 m
3 1 000 m
SO 2.1.8.1.1; 2.1.8.1.2
3
TOPIC 1 Work with numbers
2 Round to a given number of decimal places
We usually round numbers to one or two decimal places. To round
a number to one decimal place, look at the second digit after the
decimal point. If the second digit is less than 5, round down to the
lower tenth. If the second digit is 5 or more, round up to the higher
tenth. For example, 3.56 rounded to one decimal place is 3.6.
To round a number to two decimal places, look at the third digit after
the decimal point. If the third digit is less than 5, round down to the
lower hundredth. If the third digit is 5 or more, round up to the higher
hundredth. For example, 7.583 rounded to two decimal places is 7.58.
Example 2
A calculator shows that the answer to 5 3 = 1.666…
1 Round the answer correct to one decimal place.
2 Round the answer correct to two decimal places.
Solutions
1 1.7
2 1.67
We write the answer of 5 3 as 1.66… The “…” means that
the answer is a never-ending decimal. The decimal 1.67 is an
approximation of the answer of 5 3 so we use the symbol , which
means “approximately equal to”. Therefore, 5 3 1.67.
Example 3
Use your calculator to find 17 7.
1 Round the answer correct to one decimal place.
2 Round the answer correct to two decimal places.
Solutions
1 17 7 2.4
Activity 1
2 17 7 2.43
Find approximate values
1 Find an approximate value for the answer in each
expression a) to f) below.
2 Discuss how approximations can help you check your
answers.
3 Use a calculator to find each answer correct to two decimal
places.
a) 8 3
b) 12 7
c) 20 9
d) 68 13
e) 135 21
f) 925 17
4
SO 2.1.8.1.2
PAIR
TOPIC 1 Work with numbers
3 Round to a given number of significant figures
What are significant figures?
Significant figures are digits in a number that show how accurate
the number is. We count significant figures in a number from the
first non-zero digit on the left. For example, 3.82 has three significant
figures and 0.0072 has two significant figures.
We use significant figures to measure quantities such as length, mass
and capacity. An answer has more significant figures when you use
a more accurate measuring instrument. For example, a scale can
measure accurately to one-tenth of a kilogram and gives the mass
of a student as 56.3 kg. More accurate scales can measure to onethousandth of a kilogram. A scale like this gives the mass of the
student as 56.348 kg.
Rules to find the number of significant figures
The number 56.3 has three
1 Count the number of significant figures in a number from the
significant figures. The number
first non-zero digit on the left. For example, 0.0026 has two
56.348 has five significant
significant figures.
figures.
2 Trailing zeros at the end of whole numbers are not significant
figures. For example, the four zeros in 40 000 are trailing zeros,
so 40 000 has only one significant figure.
3 The zeros within a number are significant figures. For example,
the zero in 5.08 is within the number, so 5.08 has three
significant figures.
4 Trailing zeros after the decimal point are significant figures. For
example, 5.30 has one trailing zero after the decimal point, so 5.30
has three significant figures.
Example 4
Find the number of significant figures in each number.
1 71.294
2 0.011
3 20.08
4 9.50
5 1 700
6 1 520.0
Solutions
1 5
4 3
Activity 2
2 2
5 2
3 4
6 5
Find the number of significant figures
1 Read the rules for finding the number of significant figures.
2 Find the number of significant figures in each number.
a) 630
b) 1.003
c) 8.20
d) 235.887
e) 0.0056
f) 5 063
g) 14.080
h) 17 000
i) 2.00
PAIR
SO 2.1.8.1.1
5
TOPIC 1 Work with numbers
How to round to a given number of significant figures
To round to a given number of significant figures, look at the next
significant figure in the number. If the next significant figure is less than
5, round down. If the next significant figure is 5 or more, round up.
Example 5
1 Round 23.764 to three significant figures.
2 Round 23.764 to four significant figures.
Solutions
1 23.8
Activity 3
2 23.76
Round to a given number of significant figures
Round each number to three significant figures.
1 341 630
2 41.063
3 4.1920
4 571.255
5 0.01092
6 2.045
Exercise 1
Emerging issue
Information in surveys
tells us about national
health problems
such as HIV/AIDS.
This information
encourages and helps
us to support people
in need.
6
Practise approximating
1 Find the number of significant figures in each number.
a) 12.45 b) 0.0047 c) 50.06 d) 3.80 e) 5 000
2 Round each number correct to two significant figures.
a) 4 315
b) 5 628
c) 73.02
d) 0.00876
e) 4.059
f) 5.1201
3 Round 3 510 228 as follows.
a) The nearest 10
b) The nearest 100
c) The nearest 1 000
d) The nearest 10 000
e) The nearest 1 000 000
4 A survey showed that by 2001, 1 069 384 children had
been orphaned by HIV/AIDS. Round 1 069 384 as follows.
a) The nearest 10
b) The nearest 100
c) The nearest 1 000
d) The nearest 1 000 000
5 Round each decimal correct to two decimal places.
a) 56.809
b) 4.854
c) 107.227
d) 75.002
e) 0.00986
f) 1 534.505
6 Round each decimal correct to the number of decimal
places given in brackets.
a) 5.84 (one)
b) 70.335 (two)
c) 0.0852 (three)
d) 0.008036 (four)
7 Round each number correct to the number of significant
figures given in brackets.
a) 3 128 (one)
b) 71 404 (two)
c) 0.008117 (three)
d) 25.089 (four)
SO 2.1.8.1.1; 2.1.8.1.2
PAIR
SINGLE
TOPIC 1 Work with numbers
Estimation
Key concept
In mathematics, we first estimate the answer to a computation to
get an idea of the magnitude, or size, of the answer. Knowing the
magnitude of an answer helps us make fast decisions.
Estimation helps us to
check the answers to
computations.
To estimate the answer to a computation, first round the numbers to
simplify the computation. For example, a worker earns P53.85/h and
he works for 9.3 h. So, his estimated income will be P50/h 9 h = P450.
Estimation is an approximation of a quantity. When we estimate,
we guess the answer instead of actually counting, measuring or
calculating the correct answer.
You can estimate the number of cattle in a herd, the distance to a
nearby town or the quantity of fuel you need to drive from Gaborone
to Lobatse.
In the context of this chapter, estimation is a rough calculation
to find an approximate answer by rounding the numbers in a
calculation.
Always estimate the answer to a computation before you calculate the
answer. Then you can use your estimate to check your answer. When
you use a calculator, estimation prevents you making mistakes if you
accidently press the wrong keys.
Note
Example 6
1 Estimate the value of 3.142 6.68 6.68.
2 Use a calculator to find the answer correct to two decimal places.
3 Compare the answer to your estimate.
Solutions
1 3.142 6.68 6.68 3 7 7 3 50 150
2 3.142 6.68 6.68 = 140.20
3 The estimate and the answer are different because we
rounded the numbers. However, 150 and 140.20 are of a
similar magnitude.
“Of the same
magnitude” means
that the numbers are
of almost the same
size.
Example 7
1 Estimate the value of 43.87 9.35.
2 Use your calculator to find the answer. Give the answer correct
to one significant figure.
Solutions
1 43.87 9.35 40 9 360
2 43.87 9.35 = 410.1845 = 400 (correct to one significant figure)
SO 2.1.8.1.1; 2.1.8.1.2; 2.1.8.1.3
7
TOPIC 1 Work with numbers
Note
Exercise 2
Estimation skills
help us manage and
understand situations
that involve numbers
and measuring.
1 Estimate the value of each expression, then calculate the
value correct to two decimal places. Use your estimates to
check your answers.
a) 34.06 179.88 89.16
b) 497.45 117.98
c) 59.23 43.06 77.95
d) 64.15 32.72 101.46
2 Estimate the value of each expression, then calculate the
value correct to two decimal places. Use your estimates to
check your answers.
a) 19.35 11.02
b) 195.13 22.64
c) 198.95 48.32 18.77
d) 15.63 3.22 40.01
3 Use your calculator to calculate the value of each
expression. Give the answers correct to:
i) Two decimal places
ii) Two significant figures.
a) 387.4 2.09
b) 1 529.87 17.3
c) 83.72 16.78 0.26
d) 169.71 62.98 0.014
Estimate and calculate answers
SINGLE
Multi-step computations
Multi-step computations involve brackets. When you use penand-paper methods or a calculator, you have to do multi-step
computations in separate steps.
When you use pen-and-paper methods, work with an extra digit in
the intermediate steps than what the answer requires. For example,
if the answer must be correct to two decimal places, work to three
decimal places in the intermediate steps.
In multi-step computations, the order of operations is important. We
use the BODMAS rule for multi-step computations. First calculate the
expressions in brackets, followed by “of”, followed by the four basic
operations in the order of the BODMAS list.
B:
O:
D:
M:
A:
S:
8
Brackets
Of
Division
Multiplication
Addition
Subtraction
SO 2.1.8.1.1; 2.1.8.1.2; 2.1.8.1.3
TOPIC 1 Work with numbers
Example 8
1 Calculate (74.9 33.57) 2.51. Give the answer correct to
two decimal places.
2 Calculate 321.65 (2.16 3.98). Give the answer correct to
two decimal places.
Solutions
Use these calculator key sequences to find the answers on
your calculator.
1 7 4 . 9 3 3 . 5 7 2 . 5 1 (74.9 33.57) 2.51 = 103.74
2
2
.
1 6
3
.
9 8
M+ 3 2 1
.
6 5
RM
321.65 (2.16 3.98) = 52.39
If your calculator has bracket keys, then you can use this
key sequence.
3 2 1
.
6 5
(
2
.
1 6
3
.
9 8
)
When you do not have a calculator, use pen-and-paper methods to
do the computations. Your teacher will show you how to do these
examples using pen-and-paper methods. Write down the examples
and use them when you need to revise your work.
Exercise 3
Calculate multi-step computations
Calculate each computation correct to two decimal places.
1 3.55 6.80 1.09
2 (17.23 5.61) 13.9
3 274.3 18.72 8.34
4 1 033.78 (7.5 28.45)
5 (56.23 37.4) (12.77 4.81)
6 2 3.14 3.81 (3.81 8.42)
SINGLE
Case study
Programme summary of the Youth Health Organisation
The Youth Health Organisation, YOHO, is a Botswana youth
programme that is part of the Theatre and Arts Programme. YOHO
helps to educate young people about sexual health. YOHO aims to help
reduce the number of HIV/AIDS infections, teenage pregnancies and
sexually transmitted infections, or STIs, among 14 to 29 year olds.
YOHO uses programmes such as media, theatre or edutainment, and
peer education. It educates and promotes the artistic community,
writes edutainment scripts, and performs plays, poetry, and modern
Emerging issue
Sexual health is
important to win the
fight against HIV and
AIDS.
SO 2.1.8.1.2; 2.1.8.1.3
9
TOPIC 1 Work with numbers
and traditional dances. YOHO works with local music artists to inspire
youth to fight HIV/AIDS and live positively.
The Peer Education Programme, PEP, uses peer-support methods to
educate youth through talk shows, street parties, debates, condom
education, interpersonal communication, motivational talks and
life skills training. Their main focus is HIV/AIDS, STI education and
prevention, and sexuality. PEP works with other groups and nongovernmental organisations, or NGOs, to train and educate youth
about sexual health and HIV/AIDS.
[Source: Adapted from http://www.comminit.com/en/node/131030 on 23 June 2009.]
One of the aims of
Vision 2016 is to stop
the spread of HIV so
that there are no new
infections in that year.
1
2
3
4
Do you feel a need to be involved in the YOHO programme?
Discuss this with a parther.
Name two programmes that YOHO offers to youth.
Estimate then calculate the cost to get to a debate at a rural school
if the organiser travels 1 938.62 km at a rate of P2.84/km. Round
the answer correct to two decimal places.
Estimate then calculate the cost of a radio programme that lasts
23 min at a rate of P112.17/min. Round the answer correct to two
decimal places.
Key concept
Number sequences
Identify features of
number sequences.
A number sequence is an ordered set of numbers that follows a
certain rule. For example, 2; 4; 6; 8; 10; …; 30 is a number sequence
where the rule is that each member of the sequence is 2 more than
the previous member. The first member of the sequence is 2 and the
last member of the sequence is 30.
There are two types of sequences: finite sequences and infinite
sequences. A finite sequence has a last member. For example, 100 is the
last member of the sequence 10; 20; 30; …; 100. An infinite sequence
has a never-ending number of members or we can say it extends to
infinity. An example of such a sequence is 1; 3; 5; 7; … You can always
find the next member by adding 2 to the previous member.
10
SO 2.1.8.1.2; 2.1.8.1.3
TOPIC 1 Work with numbers
Example 9
Give the first member, last member and the rule for each number
sequence.
1 12; 13; 14; 15; …; 40
2 1; 4; 7; 10; …
3 5; 10; 15; 20; …; 100
4 32; 28; 24; …; 8
5 2; 4; 8; 16; …
6 1; 2; 4; 7; 11; …; 79
Solutions
1 First member = 12; last member = 40; rule: add 1
2 First member = 1; last member: continues to infinity;
rule: add 3
3 First member = 5; last member = 100; rule: add 5
4 First member = 32; last member = 8; rule: subtract 4
5 First member = 2; last member: continues to infinity;
rule: multiply by 2
6 First member = 1; last member = 79; rule: add 1; 2; 3; …
Note
The rule of a number
sequence describes
the relationship
between the numbers
in the sequence.
Example 10
Find the rule for each number sequence and use the rule to find
the missing numbers.
1 1; 4; 7; 10; …; …; …; …; 25
2 1; 4; 16; 64; …; …; …; …; 65 536
3 10; 5; 0; 5; …; …; …; …; 30
Solutions
1 Rule: add 3; missing numbers: 13; 16; 19; 22
2 Rule: multiply by 4; missing numbers: 256; 1 024; 4 096; 16 384
3 Rule: subtract 5; missing numbers: 10; 15; 20; 25
Activity 4
Describe number sequences
1 A number sequence is an ordered set of numbers that
follows a certain rule.
a) Explain what “an ordered set of numbers” means.
b) Explain what “follows a certain rule” means.
2 Write any number sequence that has six members.
a) Write the rule for the number sequence.
b) Write the first member of the number sequence.
c) Write the last member of the number sequence.
3 You are given the number sequence 1; 7; 14; 22; …;
…; …; …
a) Find the missing numbers.
b) Find the total of the numbers in the number sequence.
PAIR
SO 2.1.8.2.2
11
TOPIC 1 Work with numbers
Exercise 4
SEPTEMBER
SUNDAY
MONDAY
TUESDAY
WEDNESDAY
3
4
5
6
10
11
12
13
17
18
19
20
25
26
27
24
31
12
SO 2.1.8.2.2
Work with number sequences
1 Describe each number sequence.
a) 1; 4; 7; 10; 13; 16; 19; 22
b) 1; 2; 4; 8; 16; 32; 64; 128
2 ; __
2
c) 18; 6; 2; __23; __29 ; __
27 81
2 Find i) the rule and ii) the missing numbers in each
number sequence.
a) __14; 1; 1__34; 2__12 ; …; …; …; …
b) 1%; 3%; 5%; …; …; …; …
c) 2.3; 3; 3.7; 4.4; …; …; …; …
3 Find the missing numbers in each number sequence.
a) 2; 5; 8; 11; …; …; …; …
b) __12 ; 1__12 ; 2__12; …; …; …; …
c) 3.25; 5.25; 7.25; …; …; …; …
4 Find the sum of the numbers in each number sequence.
a) 1; 3; 5; 7; 9; 11; 13; 15; 17; 19; 21; 23
b) 2; 6; 18; 54; 162; 486; 1 458; 4 374; 13 122
c) 23; 15; 7; 1; 9; 17; 25; 33; 41; 49; 57
5 Look at the calendar of September 2012 and
answer the questions.
a) Write and describe the number sequence in
2012
the second row of the calendar.
b)
Write and describe the number sequence in
1
2
the first column of the calendar.
7
8
9
c) Start at Monday, 4 September 2012 and
move repeatedly one position to the right
14 15 16
and one position down. Write the numbers
21 22 23
as you move. Do these numbers form a
sequence? If so, describe the sequence.
28 29 30
d) Find two similar sequences on the calendar
and write them down.
e) Start at Friday, 1 September 2012 and move repeatedly
one position to the left and one position down.
Write the numbers as you move and describe the
number sequence.
f ) Add the numbers in the first two columns of the
calendar. Look out for short methods such as
4 1 5 8 = 10 8 = 18.
g) Explain why the total of the second column is 4 more
than the total of the first column.
h) Use the fact in g) to write the totals of the other
columns of the calendar.
THURSDAY
FRIDAY
SATURDAY
SINGLE
TOPIC 1 Work with numbers
Patterns in nature
Nature consists of patterns. You can see examples of these patterns in
the spirals of pineapples, pine cones, sunflower seeds, seashells and
snail shells. You can also see nature’s patterns in the number of petals
on flowers or leaves on a twig.
Fibonacci numbers
Nature’s patterns are based on Fibonacci numbers. The Fibonacci
sequence is 1; 2; 3; 5; 8; 13; 21; 34; … The rule is to add the previous
two members to get the next member of the sequence.
Activity 5
Investigate patterns in nature
1 Find examples of patterns in plants, flowers, fruits and
shells. Study the examples and identify the spirals.
2 Count the number of petals on different flowers. Use a table
to record these numbers and the names of the flowers.
3 Look at the number of petals on flowers you recorded. Are any
of these numbers Fibonacci numbers? Discuss your results.
PAIR
Mathematical puzzles
Key concept
Mathematical puzzles are puzzles that need mathematics to solve
them. You need to work with numbers and relationships between
numbers, draw shapes, complete tables, and use logical reasoning to
solve mathematical puzzles.
Apply your
mathematical
knowledge and skills
to solve mathematical
puzzles.
Activity 6
Investigate square numbers
GROUP
You need 50 counters. Use your
counters to build this sequence.
1
4
9
1 Draw the sequence in your exercise book. Write the
number of counters below each group in the sequence.
2 Describe the pattern in words.
3 Determine how many counters you need to build the
fourth group in the sequence.
4 Use your counters to build the fourth and fifth groups in
the sequence.
5 Draw these two groups in your exercise book. Write the
number of counters in each group below each drawing.
6 Describe the pattern in the number sequence below the
drawings.
Patterns occur in nature
in different ways.
SO 2.1.8.2.1; 2.1.8.2.2
13
TOPIC 1 Work with numbers
7 Determine the sixth and seventh numbers in the sequence.
Write these numbers in your exercise book.
8 We call these numbers square numbers. Explain why we
call them square numbers.
Exercise 5
Solve mathematical puzzles
1 Naledi uses counters to build this
sequence. Look at her
sequence and answer
the questions.
a) Draw the sequence in your exercise book. Write the
number of counters below each group in the sequence.
b) Determine how many counters Naledi needs to build
the fourth group.
c) Draw the fourth and fifth groups and write the
number of counters below each drawing.
d) Look at the numbers only. Determine how many
counters Naledi needs to build the sixth group.
e) Draw the sixth group in your exercise book and check
your answer in d).
2 The rows, columns and diagonals of each square add up to
the number shown next to the square. Copy the squares
into your exercise book and fill in the missing numbers.
a)
1
b)
14
12 6
9
10
13
2 16
34
17 24 1
15
14
4
13
10 12
22
65
21 3
18 25 2
3 The rows, columns and diagonals of this square add up to
the same number. Each of the digits 1 to 9
8
can appear in the square only once. Copy the
square into your exercise book then fill in the
5 7
missing numbers.
4 9
4 The sum along each side of the triangle is
the same and the sum of the digits at the
vertices is 6. Fill in the digits 1 to 9 in the
circles to make these statements true.
5 Calculate the values of A, B and C
that make all of these statements true.
a) A B = 10
b) A C = 4
c) C = B 2
14
SO 2.1.8.2.1
SINGLE
TOPIC 1 Work with numbers
Summary
ü We approximate answers of computations
by rounding numbers to the nearest
power of 10, to a given number of
significant figures or to a given number of
decimal places.
ü We identify significant figures in the
following ways.
ü We count significant figures from the
first non-zero digit on the left. For
example, 0.123 has three significant
figures.
ü All zeros within a number are
significant. For example, 51 008 has
five significant figures.
ü Trailing zeros are not significant unless
they are the last digits after a decimal
point. For example 0.70 has two
significant figures.
ü To round a number to two decimal places
or to two significant figures, look at the
next digit. If the next digit is 5 or more,
round up. For example 23.455 rounded
to two decimal places is 23.46. If the
next digit is less than 5, round down. For
example, 23.454 rounded to two decimal
places is 23.45.
ü The rule of a number sequence describes
the relationship between the members
of the sequence. We use the rule of
a number sequence to find missing
members of the sequence.
Revision
3 Round each number correct to two
significant figures.
a) 1 057
b) 21 300
c) 32.87
d) 0.00118
4 A piece of rope is 638.62 cm long.
You want to cut the rope into 19 equal
pieces.
a) Round the length of the rope to two
significant figures.
b) Estimate the length of each piece of
rope.
c) Calculate the actual length of each
piece of rope correct to two decimal
places.
5 Calculate correct to two decimal places.
4 783.25 (168.55 94.32)
6 Find the missing numbers in each number
sequence.
a) 1; 3; 5; 7; …; …; …
b) 1; 3; 9; 27; …; …; …
c) 100; 10; 0.1; …; …; …
7 Calculate the answers correct to two
decimal places.
a) 17.005 45.503
b) 89.27 25.0333
c) 8 251.57 0.411
d) 368.29 13.72
e) 290.57 12.87 17.31
8 Calculate the answers correct to two
decimal places.
a) 6 193.45 3 372.334
b) 34.67 12.874 3.88
c) 23.782 3.815 15.235
d) 21.43(45.67 8.442) 211.72
e) 5 108.75 3.142(17.6 2.58)2
1 Round 3 056 to the nearest:
a) 10
b) 100
c) 1 000.
2 Round each decimal correct to two
decimal places.
a) 2.8741
b) 200.075
c) 0.0082
15