Adding & Subtracting Decimals Worksheets, Grade 6 (6.NS.B.3) – Free PDF + Answer Key

First page of the adding & subtracting decimals practice worksheet

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PDFs print on US Letter paper. Free for classroom and home use.

Step-by-step math videos on the Math With Mr DJ YouTube channel →

Key idea

Line up the points, fill with zeros. 7.2 − 3.45 → 7.20 − 3.45 = 3.75. The zero is a placeholder, not a new value — 9.3 and 9.30 are the same number.

Sample problems

Compute 6.2 + 3.45.
Compute 15.08 + 2.7.
Compute 9.3 − 4.17.
Compute 100 − 38.64.

Common mistakes to watch for

Right-aligned the digits instead of the decimal points (3.5 under .75) → 3.80 or 6.10. Fill with a zero, then add.
Subtracted the smaller digit from the larger in each column (getting 5.46) instead of regrouping.
Misplaced $0.08 as $0.80 — the tenths place is empty, so it needs the 0.

The answer key explains each one, so you can tell what a wrong answer means.

How to use this set

Teach with the slides (about 15 minutes), or watch the video together.
Practice with the worksheet. Questions climb from fluency to application to reasoning.
Check understanding with the exit ticket, and send the homework home.
Mark with the answer key — each answer shows the steps and the most likely mistake.