Add and Subtract Rational Numbers, Challenge Answer Key

Grade 7 rational numbers: adding and subtracting positive and negative fractions, mixed numbers, and decimals. Monday practice at the challenge level.

Name: Date: Class:

Lesson Notes

Pick one form for the whole problem. If fractions and decimals are mixed, either turn every decimal into a fraction or every fraction into a decimal, whichever is cleaner.

Worked example

$-3.125 - 2\tfrac{3}{4}$: eighths and quarters both turn into exact decimals, so use decimals.

$-3.125 - 2.75 = -5.875$

Use a fraction when a denominator like 3, 6, or 12 would make a decimal repeat.
Grouping symbols come first. Subtracting a group changes the sign of every term inside it.
For a story, write the expression first, then compute it.

Estimate first. Round each number to the nearest whole number to see whether your answer is close.

25 problems. Work each one on the canvas under it (pen, eraser and clear are in the canvas toolbar; drag the handle below the canvas for more room). Enter your answer in the box (the keypad under it has fractions, exponents, square roots, pi, the degree sign and the symbols < > ≤ ≥ ≠). When a Unit row is shown, tap the unit for your answer. Then press Check. Write fraction answers as improper fractions in lowest terms. Write decimal answers as decimals. The eye at the right of the row shows or hides the worked solution.