Adding & Subtracting Rational Numbers

Adding Fractions

100

-5 1/3 + 8 2/3

3 1/3 

200

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

3 1/6

300

-18 7/9 + 7 4/9

-11 1/3

400

3 1/4 + 7 3/4

11

500

-12 7/8 + -2 1/2

- 15 3/8

Subtracting Fractions

100

-8 1/2 - 4

-12 1/2

200

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

9 1/88888

300

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

-15 1/5

400

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

17 5/14

500

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

5 1/3

Adding Decimals

100

-13.4 + 8.6

-4.8

200

7.51 + 22.08

29.59

300

-41.90 + 22

19.90

400

-117.4 + 8.93

-108.47

500

- 328.17 + 63.40

-264.77

Subtracting Decimals

100

-3.7 - 14.9

-18.6

200

4.07 - 22.43

-18.36

300

-81.36 - 41.93

-123.29

400

7.85 - ( -31.03)

38.88

500

131.78 - 206.14

-74.36

Math Rules

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

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

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

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

Change to have common denominators

500

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

Line up the decimal point (and the place values)