Boba Maths

Year 6 · Arithmetic skills · Skill 4A

Skill 4A: Subtracting a decimal from a whole number

Take a decimal number with up to 3 decimal places away from a whole number.

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Each file is an editable Word document (.docx) with 25 questions in five columns. It opens in Word, Google Docs, Pages and LibreOffice, so you can change questions or add working space before printing.

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Worked examples

To take a decimal from a whole number, give the whole number the same number of decimal places by adding zeros, then use column subtraction.

Example 1

One whole number, two decimal places

12 − 4.65

  1. A whole number has an invisible decimal point on its right. Write 12 as 12.00 so that both numbers have 2 decimal places. The extra zeros do not change the value.
  2. Line up the decimal points, one under the other. Subtract from right to left, exchanging when needed. The zeros you added are shown in grey.
    10211.09010
    −4.65
    7.35
  3. Work through each column:
    • hundredths: 10 − 5 = 5. 0 is smaller than 5 and the tenths column is 0, so exchange across the zero: take 1 from the ones column, leave 9 in each zero column and make 10 here.
    • tenths: 9 − 6 = 3.
    • ones: 11 − 4 = 7. 1 (after lending 1 away) is smaller than 4, so exchange: take 1 from the tens column to make 11.
    • tens: 0 − 0 = 0.
    Bring the decimal point straight down into the answer.
  4. So 12 − 4.65 = 7.35. Check by adding: 7.35 + 4.65 = 12.

Answer: 7.35

Example 2

Three decimal places

95 − 8.372

  1. A whole number has an invisible decimal point on its right. Write 95 as 95.000 so that both numbers have 3 decimal places. The extra zeros do not change the value.
  2. Line up the decimal points, one under the other. Subtract from right to left, exchanging when needed. The zeros you added are shown in grey.
    98514.0909010
    −8.372
    86.628
  3. Work through each column:
    • thousandths: 10 − 2 = 8. 0 is smaller than 2 and the hundredths column is 0, so exchange across the zero: take 1 from the ones column, leave 9 in each zero column and make 10 here.
    • hundredths: 9 − 7 = 2.
    • tenths: 9 − 3 = 6.
    • ones: 14 − 8 = 6. 4 (after lending 1 away) is smaller than 8, so exchange: take 1 from the tens column to make 14.
    • tens: 8 − 0 = 8.
    Bring the decimal point straight down into the answer.
  4. So 95 − 8.372 = 86.628. Check by adding: 86.628 + 8.372 = 95.

Answer: 86.628

Top tips

  • Add a decimal point and enough zeros to the whole number first.
  • Keep the decimal points in a straight line all the way down.
  • Check by adding your answer to the number you took away.

Watch out for

  • Lining the digits up on the right instead of on the decimal point, so 12 sits over the wrong digits of 4.65.
  • Forgetting the decimal point in the answer.

Try some questions

These are from the worksheet. Work each one out, then open it to check.

  1. 8 − 3.7 =
    Show the answer

    4.3

  2. 43 − 7.56 =
    Show the answer

    35.44

  3. 84 − 7.943 =
    Show the answer

    76.057

  4. 94 − 7.683 =
    Show the answer

    86.317

All arithmetic skills

Skill 1ASkill 1BSkill 2ASkill 2BSkill 3ASkill 4BSkill 5ASkill 5BSkill 6ASkill 6BSkill 6CSkill 6DSkill 7ASkill 8ASkill 9ASkill 10ASkill 10BSkill 10CSkill 11ASkill 11BSkill 11CSkill 12ASkill 13ASkill 14A

Arithmetic skills overview · Year 6 overview