Adding Fractions
Subtracting Fractions
Adding Decimals
Subtracting Decimals
Math Rules
100

`-5 1/3 + 8 2/3`

`3 1/3 `

100

`-8 1/2 - 4`

`-12 1/2`

100

-13.4 + 8.6

-4.8

100

-3.7 - 14.9

-18.6

100

Part 1 - what is the sign of the sum of 2 negative numbers? 

Part 2 - what is the sign of the sum of 2 positive numbers?

Part 1 - negative 

Part 2 - positive

200

`4 5/6 + (-1 2/3)`




`3 1/6`

200

`7 3/8 - (-2 1/8)`

`9 1/2`

200

7.51 + 22.08

29.59

200

4.07 - 22.43

-18.36

200

How can you know what the sign will be for the sum of a negative and a positive number?

The answer will have the same sign as the number with the greatest absolute value. (Larger absolute value wins the sign.)

300

`-18 7/9 + 7 4/9`

`-11 1/3`

300

`-26 2/5 - ( -11 1/5)`

`-15 1/5`

300

-41.90 + 22

19.90

300

-81.36 - 41.93

-123.29

300

How can you change a subtraction sentence into an addition sentence? 

Add the Opposite   OR

Keep, Change, Change

Example: 4.5 - 6.5 = 4.5 + (-6.5)

400

`3 1/4 + 7 3/4`

11

400

`14 1/7 - ( -3 3/14)`

`17 5/14`

400

-117.4 + 8.93

-108.47

400

7.85 - ( -31.03)

38.88

400

What has to be done before you can add or subtract fractions?

Change to have common denominators

500

`-12 7/8 + -2 1/2`

`- 15 3/8`

500

`-5 3/6 - ( -10 2/3)`

`5 1/3`

500

- 328.17 + 63.40

-264.77

500

131.78 - 206.14

-74.36

500

What has to be done before you can add or subtract decimals?

Line up the decimal point (and the place values)