Math Drill Pages

Adding Decimals Worksheet

Eighteen decimal addition problems with tenths and hundredths. In Part A the problems are already written in columns with the decimal points lined up. In Part B students rewrite each problem in columns themselves, and the two numbers often have a different number of decimal places, like 43.32 + 32.9 or 27 + 15.46. The answer key is on page 2.

Grade
Grade 5
Problems
18
Time
About 15 minutes
Standard
5.NBT.B.7
Download PDF (US Letter) Download PDF (A4)

Two pages: the worksheet, then the answer key. No sign-up needed.

Worksheet preview

Part A: Add in columns Line up the decimal points, then add.

  1. 27.57+ 27.4254.99
  2. 24.4+ 31.355.7
  3. 39.7+ 24.864.5
  4. 08.6+ 34.743.3
  5. 28.9+ 09.238.1
  6. 09.2+ 28.237.4
  7. 26.39+ 39.9166.30
  8. 45.71+ 19.1864.89

Part B: Line them up yourself Rewrite each problem in columns with the decimal points lined up.

  1. 31.8 + 46.47 = 78.27
  2. 27.4 + 24 = 51.4
  3. 42.1 + 4.78 = 46.88
  4. 16.1 + 27 = 43.1
  5. 40.4 + 41 = 81.4
  6. 39.1 + 27 = 66.1
  7. 31 + 19.77 = 50.77
  8. 28 + 35.65 = 63.65
  9. 13.62 + 17.5 = 31.12
  10. 22.8 + 32.39 = 55.19

Tips for teachers and parents

  • The one rule: line up the decimal points. Then every digit sits under a digit of the same place value.
  • A whole number has a decimal point at its end that we usually do not write. 27 is the same as 27.0 or 27.00.
  • Filling empty places with zeros (32.9 becomes 32.90) makes the columns easier to see and does not change the value.
  • Bring the decimal point straight down into the answer before adding.

Common mistakes

  • Lining up the last digits instead of the decimal points, so 32.9 + 4.22 is added like 329 + 422.
  • Forgetting to carry across the decimal point, for example when the tenths add up to more than 9.

What to practice next

Subtracting decimals uses the same line-up rule, plus regrouping across the decimal point.

Frequently asked questions

How do you add decimals?

Write the numbers in columns with the decimal points lined up, fill any empty places with zeros, then add as with whole numbers and bring the decimal point straight down.

What grade learns adding decimals?

The Common Core standard 5.NBT.B.7 covers adding decimals to hundredths in fifth grade. Many fourth graders add tenths and hundredths with money first.

Is there an answer key?

Yes, page 2 has every answer. Part A answers keep the same number of decimal places as the problem.