Download Decimals

Test
24-May-17
Level F – Fri 12th Dec
Revise
Chapter 13 - Decimals
Chapter 7 – Scientific Notation
Chapter 37 – Drawing Skills
Chapter 47 – Time / Distance / Speed
Decimals
24-May-17
Revision
Learning Intention
1.
To revise Level F work.
Success Criteria
1. Add and subtract decimals
2. To multiply and divide
decimal numbers
3. To round to any number of
decimal places
4. To round to any number of
significant figures
Decimals
24-May-17
Revision Level E
1. What does 6 stand for in 0.26 ?
6 hundredths
2. Name one number which lies between 0.1 and 0.2 ?
0.11
3. Round to 1 decimal place 34.055 34.1
4. Calculate 4.76 x 100
Shop A 80p
Shop B 79p
476
5. Calculate 567.89 ÷ 1000
0.56789
B is
cheaper!
6. Shop A sell 25 CD’s for £20 and Shop B sells
40 CD’s for £31.40. Which shop is the cheapest.
Decimals
24-May-17
Addition & Subtraction
Example : 3.2 + 0.487 + 5.73
3.200
0.487
5.730
9.417
1 11
Keep point in
line
Decimals
24-May-17
Addition & Subtraction
Example : 6.2 – 3.19 + 1.783
6.200
+1.783
7.983
3.190
4.793
Add first
Then subtract
Decimals
24-May-17
Simple Multiplication
Example 1 : 0.6 x 0.4
6 x 4 = 24
0. 24
2 digits after
decimal place
Example 2 : 0.09 x 0.3
9 x 3 = 27
0. 027
3 digits after
decimal place
Decimals
24-May-17
Simple Multiplication
Example 3 : 0.071 x 0.5
71 x 5 = 355
4 digits after
decimal place
0. 0355
Decimals
24-May-17
Division of a Decimal
Do not attempt to divide by a decimal,
multiply the divisor so it is a whole number first.
Example 1 : 3.5 ÷ 0.7
35 ÷ 7 = 5
x 10
x 10
Example 2 : 0.8 ÷ 0.2
8÷2= 4
Decimals
24-May-17
Division of a Decimal
Do not attempt to divide by a decimal,
multiply the divisor so it is a whole number first.
Example 3 : 0.036 ÷ 0.04
3.6 ÷ 4 = 0.9
x 100
Example 4 : 24 ÷ 3000
24 ÷ 3÷1000 = 0.008
Decimals
24-May-17
Rounding to Any Number of Decimal Places
When rounding to :
1 decimal place look at 2nd decimal figure
e.g. 2.46
2 decimal place look at 3rd decimal figure e.g. 6.456
3 decimal place look at 4th decimal figure
e.g. 3.7846
4 decimal place look at 5th decimal figure
e.g. 13.1146
Decimals
24-May-17
Rounding to Any Number of Decimal Places
Example : The number 4.2615937
Rounded to 1 decimal place, the number is 4.3
Rounded to 2 decimal place, the number is 4.26
Rounded to 3 decimal place, the number is 4.262
Rounded to 4 decimal place, the number is 4.2616
Significant Numbers
24-May-17
In mathematics a figure or digit is significant
if it gives an idea of both:
(i) Quantity
(ii) Accuracy
IMPORTANT : If zero’s are employed just to position the decimal point
then they are considered NOT significant.
e.g.
506 cm
Has 3 significant figures.
50.6 cm Has 3 significant figures.
0.506 cm Has 3 significant figures.
0.00506 cm Has 3 significant figures.
Significant Numbers
24-May-17
IMPORTANT : When dealing with WHOLE NUMBERS you need
More information before you can tell if trailing zero’s are significant.
Question ? How many significant figures is this number to.
360
Is it 2 or 3 !!!
3
If I said 359 to the nearest ten is 360. How many significant figures. 2
If I said there are 360 deg. in a circle. How many significant figures.
YOU NEED TO KNOW THE CONTEXT OF THE QUESTION WHEN
DEALING WITH WHOLE NUMBERS WITH TRAILING ZEROS.
WORK OUT WHAT THE ZERO MEANS
Significant Figures
24-May-17
Decimals
0.001090
To the left of
The number
Middle of
the number
To the right of
the number
Always Significant
Not Significant
Always Significant
Whole Numbers
03060
To the left of
The number
Middle of
the number
? Depends
More Info.
Not Significant Always Significant Read Question