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Math 7 · Unit 4: Decimals · Cambridge Lower Secondary Maths Stage 7

4.5 Making decimal calculations easier

37 questions · e.g. 4.9 × 6

Practice

Questions

  1. 1. Match each of these decimals to its equivalent fraction.

    • 0.4
    • 0.7
    • 0.05
    • 0.06
    • 0.02
    • 6/100
    • 4/10
    • 2/100
    • 7/10
    • 5/100
    Check

  2. 2. Complete the working to make this calculation easier. 150 × 0.2

    0.2 =210= 2 ÷ 10150 × 2 ÷ 10 = 150 ÷ 10 ×= 15 ×=

    Fill the blanks with these.

    Check

  3. 3. Complete the working to make this calculation easier. 70 × 0.3

    0.3 =310= 3 ÷ 1070 × 3 ÷ 10 = 70 ÷×=×=

    Fill the blanks with these.

    Check

  4. 4. Complete the working to make this calculation easier. 120 × 0.6

    0.6 =610=÷120 ×÷= 120 ÷×=×=

    Fill the blanks with these.

    Check

  5. 5. For each of the following, complete the working to make the calculation easier. 1200 × 0.03

    0.03 =3100= 3 ÷ 1001200 × 3 ÷ 100 = 1200 ÷ 100 ×= 12 ×=

    Fill the blanks with these.

    Check

  6. 6. For each of the following, complete the working to make the calculation easier. 900 × 0.05

    0.05 =5100= 5 ÷ 100900 × 5 ÷ 100 = 900 ÷×=×=

    Fill the blanks with these.

    Check

  7. 7. For each of the following, complete the working to make the calculation easier. 700 × 0.04

    0.04 =4100=÷700 ×÷= 700 ÷×=×=

    Fill the blanks with these.

    Check

  8. 8. Zara uses this method to multiply a number by the decimal 0.5. Use Zara's method to work out 20 × 0.5.

    0.5 is the same as 1/2.40 × 0.5 is the same as 40 × 1/2,which is the same as 40 ÷ 2.So, 40 ÷ 2 = 20.Tip: the easiest way to work out0.5 × a number is to work out the number ÷ 2.
    Check

  9. 9. Zara uses this method to multiply a number by the decimal 0.5. Use Zara's method to work out 50 × 0.5.

    0.5 is the same as 1/2.40 × 0.5 is the same as 40 × 1/2,which is the same as 40 ÷ 2.So, 40 ÷ 2 = 20.Tip: the easiest way to work out0.5 × a number is to work out the number ÷ 2.
    Check

  10. 10. Zara uses this method to multiply a number by the decimal 0.5. Use Zara's method to work out 16 × 0.5.

    0.5 is the same as 1/2.40 × 0.5 is the same as 40 × 1/2,which is the same as 40 ÷ 2.So, 40 ÷ 2 = 20.Tip: the easiest way to work out0.5 × a number is to work out the number ÷ 2.
    Check

  11. 11. Zara uses this method to multiply a number by the decimal 0.5. Use Zara's method to work out 48 × 0.5.

    0.5 is the same as 1/2.40 × 0.5 is the same as 40 × 1/2,which is the same as 40 ÷ 2.So, 40 ÷ 2 = 20.Tip: the easiest way to work out0.5 × a number is to work out the number ÷ 2.
    Check

  12. 12. Zara uses this method to multiply a number by the decimal 0.5. Use Zara's method to work out 52 × 0.5.

    0.5 is the same as 1/2.40 × 0.5 is the same as 40 × 1/2,which is the same as 40 ÷ 2.So, 40 ÷ 2 = 20.Tip: the easiest way to work out0.5 × a number is to work out the number ÷ 2.
    Check

  13. 13. Zara uses this method to multiply a number by the decimal 0.5. Use Zara's method to work out 23 × 0.5.

    0.5 is the same as 1/2.40 × 0.5 is the same as 40 × 1/2,which is the same as 40 ÷ 2.So, 40 ÷ 2 = 20.Tip: the easiest way to work out0.5 × a number is to work out the number ÷ 2.
    Check

  14. 14. Complete the working to make this calculation easier. 2.3 × 9

    2.3 × 9= 2.3 × (10 − 1)= 2.3 × 10 − 2.3 × 1=−=

    Fill the blanks with these.

    Check

  15. 15. Complete the working to make this calculation easier. 5.7 × 9

    5.7 × 9= 5.7 × (10 − 1)= 5.7 × 10 − 5.7 × 1=−=

    Fill the blanks with these.

    Check

  16. 16. Complete the working to make this calculation easier. Use the place value method. 0.3 × 270

    0.3 × 270=310× 270= 3 ÷ 10 × 270= 3 × 270 ÷ 10= 3 ×= 3 ×+ 3 ×=+=

    Fill the blanks with these.

    Check

  17. 17. Complete the working to make this calculation easier. Use the place value method. 0.07 × 4300

    0.07 × 4300=7100× 4300= 7 ÷ 100 × 4300= 7 × 4300 ÷ 100= 7 ×= 7 ×+ 7 ×=+=

    Fill the blanks with these.

    Check

  18. 18. Question 7a: work out 0.4 × 630.

    Check

  19. 19. Question 7b: work out 0.8 × 250.

    Check

  20. 20. Question 7c: work out 0.07 × 5100.

    Check