Download Unit 1 Study Guide Information

Adding& Subtracting decimal numbers
Step 1: Write down the numbers, one under the other, line up decimals
Step 2: Put in zeros so the numbers have the same length
Step 3: Then add/ subtract normally, remembering to put the decimal point in the answer
Practice:
3) 112.83 - 37.94 =
1) 100- 65.27 =
4) 112.83 + 37.94 =
2) 40+ 21.32 =
Multiplying decimals numbers
Step 1: Write down the numbers.
Step 2: Count your dp’s for each number
Step 3: Multiply the numbers as if they
were whole numbers.
Step 4: Move your decimal point in the
answer from right to left.
Practice:
=
3.1 × 5.06 =
Dividing decimal numbers
Step 1: If the divisor is not a whole
number, move the decimal place to the
right to make it a whole number. Then
move the decimal place in the dividend
the same number of places to the right
Step 2: Divide as usual. Add zeros to the
right of the dividend and keep dividing
until you get a 0 remainder, or until a
repeating pattern shows up.
Step 3: Put the decimal point in the
quotient/answer directly above where
the decimal point now is in the dividend.
Step 4: Check your answer against your
estimate to see if it's reasonable.
Prime Numbers (Prime Factorization)
A prime number can be divided evenly only by 1, or itself. The prime numbers between
2 and 100 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67,
71, 73, 79, 83, 89 and 97. Prime Factorization is a number written as the product
of its prime factors. Ex. 10 = 2 * 5 or 24 = 23 * 3 or 24 = 2*2*2*3.
GCF
The greatest common factor, or GCF, is the greatest factor that divides two numbers. To
find the GCF of two numbers:
1) Find the factors of each number by: listing all the factors, prime factorization, upsidedown cake or ladder, or T-Chart.
2) If the only common factor is 1; the GCF is 1 and the numbers are called relatively prime.
Math Unit 1 Study guide
Created by: Ms. Jackson& Mrs. Rogers
(update 9/6/2013)
Practice:
1) Find the GCF of this pair of numbers 14 and 49.
2) What is the GCF of 15 and 75?
a) 5
b) 3
c) 15
d) 1
3) What is the GCF of 14 and 24?
a) 2
b) 3
c) 7
d) 6
LCM
The least common multiple (LCM) of two numbers is the smallest number (not zero)
that is a multiple of both. For example, to find the LCM of 3 and 4 you will list the multiples of 3,
then list the multiples of 4, and identify the least multiple they have in common.
Practice
1) What is the LCM of 30 and 45?
a) 5 b) 90 c) 120 d) 150
2) What is the LCM of 12 and 80?
a) 80 b) 12 c) 4
d) 160
3)Find the LCM of 26 and 20.
4) Find the LCM of 15, 30, and 20.
Distributive Property
Distributive property is used to rewrite a simple addition problem using a common factor.
When you multiply a number
times a sum, you can:
(1) Find the sum first and then
multiply, or
(2) Multiply by each number
in the sum and then add
Examples:
Factor out expression:
6 (10 + 4) = 6 * 14
= 84
6 (10 + 4) = 6*10 + 6 * 4
= 60 + 24
= 84
Rewrite expression using
distributive property:
Math Unit 1 Study guide
Created by: Ms. Jackson& Mrs. Rogers
Use distributive
property to rewrite
expression
a. 5
Factor out the
expression
(update 9/6/2013)
Dividing Fractions
Step 1: SAME (copy the 1st fraction how
it is)
Step 2: CHANGE (division symbol to
multiplication)
Step 3: FLIP ( the second fraction)
Step 4: Multiply the fractions ACROSS
Step 5: Simply your answer
Practice:
÷ =
÷8=
When dealing with mixed numbers,
before you apply steps 1-5 CONVERT
your MIXED # to IMPROPER FRACTION.
1 ÷ =
Long division :D M S B
Long division is an algorithm that repeats the basic steps of
1) Divide;
2) Multiply & Subtract;
3) Bring down the next digit.
1. Divide.
2. Multiply & subtract.
t o
3. Drop down the next digit.
t o
t o
2
2 )5 8
2
2)58
-4
1
29
2)58
-4↓
18
Two goes into 5 two
times, or 5 tens ÷ 2 = 2
whole tens -- but there
is a remainder!
To find it, multiply 2 × 2
= 4, write that 4 under
the five, and subtract
to find the remainder of
1 ten.
Next, drop down the 8 of the
ones next to the leftover 1
ten. You combine the
remainder ten with 8 ones,
and get 18.
Practice:
1.
3)128
2.
3)95
3.
6)4267
4.
4)2845
Math Unit 1 Study guide
Created by: Ms. Jackson& Mrs. Rogers
(update 9/6/2013)