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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 831 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 29 × 46? (a) 15000 (b) 150 (c) 1500
  2. 2.Best estimate of 815 + 743? (a) 1300 (b) 1700 (c) 1500
  3. 3.Best estimate of 126 + 245? (a) 100 (b) 300 (c) 500
  4. 4.Best estimate of 93 × 64? (a) 54000 (b) 540 (c) 5400
  5. 5.Best estimate of 614 + 535? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 385 + 643? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 58 × 47? (a) 300 (b) 30000 (c) 3000
  8. 8.Best estimate of 667 + 328? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 26 × 31? (a) 900 (b) 9000 (c) 90
  10. 10.Best estimate of 511 + 305? (a) 800 (b) 1000 (c) 600
  11. 11.Best estimate of 73 × 26? (a) 210 (b) 21000 (c) 2100
  12. 12.Best estimate of 129 + 541? (a) 800 (b) 400 (c) 600
  13. 13.Best estimate of 156 + 260? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 269 + 251? (a) 800 (b) 600 (c) 400
  15. 15.Best estimate of 17 × 40? (a) 8000 (b) 80 (c) 800
  16. 16.Best estimate of 38 × 20? (a) 800 (b) 80 (c) 8000
  17. 17.Best estimate of 478 + 619? (a) 1300 (b) 1100 (c) 900
  18. 18.Best estimate of 26 × 53? (a) 15000 (b) 1500 (c) 150
  19. 19.Best estimate of 278 + 351? (a) 900 (b) 700 (c) 500
  20. 20.Best estimate of 58 × 82? (a) 48000 (b) 4800 (c) 480
  21. 21.Best estimate of 53 × 50? (a) 250 (b) 2500 (c) 25000
  22. 22.Best estimate of 313 + 481? (a) 800 (b) 1000 (c) 600
  23. 23.Best estimate of 632 + 158? (a) 800 (b) 600 (c) 1000
  24. 24.Best estimate of 54 × 37? (a) 200 (b) 2000 (c) 20000
  25. 25.Best estimate of 83 × 86? (a) 72000 (b) 720 (c) 7200
  26. 26.Best estimate of 98 × 41? (a) 400 (b) 40000 (c) 4000
  27. 27.Best estimate of 73 × 96? (a) 700 (b) 7000 (c) 70000
  28. 28.Best estimate of 46 × 49? (a) 25000 (b) 250 (c) 2500
  29. 29.Best estimate of 30 × 58? (a) 18000 (b) 1800 (c) 180
  30. 30.Best estimate of 36 × 76? (a) 3200 (b) 320 (c) 32000
  31. 31.Best estimate of 28 × 73? (a) 2100 (b) 21000 (c) 210
  32. 32.Best estimate of 27 × 21? (a) 600 (b) 60 (c) 6000
  33. 33.Best estimate of 96 × 33? (a) 3000 (b) 300 (c) 30000
  34. 34.Best estimate of 767 + 640? (a) 1600 (b) 1400 (c) 1200
  35. 35.Best estimate of 62 × 82? (a) 480 (b) 4800 (c) 48000
  36. 36.Best estimate of 441 + 629? (a) 1200 (b) 800 (c) 1000
  37. 37.Best estimate of 334 + 418? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 23 × 59? (a) 120 (b) 12000 (c) 1200
  39. 39.Best estimate of 736 + 211? (a) 1100 (b) 900 (c) 700
  40. 40.Best estimate of 19 × 96? (a) 20000 (b) 2000 (c) 200

Answer key

  1. 1500
  2. 1500
  3. 300
  4. 5400
  5. 1100
  6. 1000
  7. 3000
  8. 1000
  9. 900
  10. 800
  11. 2100
  12. 600
  13. 500
  14. 600
  15. 800
  16. 800
  17. 1100
  18. 1500
  19. 700
  20. 4800
  21. 2500
  22. 800
  23. 800
  24. 2000
  25. 7200
  26. 4000
  27. 7000
  28. 2500
  29. 1800
  30. 3200
  31. 2100
  32. 600
  33. 3000
  34. 1400
  35. 4800
  36. 1000
  37. 700
  38. 1200
  39. 900
  40. 2000

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