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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 262 · 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 20 × 72? (a) 14000 (b) 140 (c) 1400
  2. 2.Best estimate of 36 × 56? (a) 240 (b) 2400 (c) 24000
  3. 3.Best estimate of 38 × 27? (a) 120 (b) 12000 (c) 1200
  4. 4.Best estimate of 76 × 21? (a) 16000 (b) 1600 (c) 160
  5. 5.Best estimate of 97 × 93? (a) 90000 (b) 900 (c) 9000
  6. 6.Best estimate of 129 + 131? (a) 400 (b) 200 (c) 0
  7. 7.Best estimate of 92 × 84? (a) 720 (b) 72000 (c) 7200
  8. 8.Best estimate of 314 + 470? (a) 600 (b) 800 (c) 1000
  9. 9.Best estimate of 648 + 665? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 61 × 13? (a) 6000 (b) 60 (c) 600
  11. 11.Best estimate of 18 × 74? (a) 1400 (b) 14000 (c) 140
  12. 12.Best estimate of 93 × 47? (a) 450 (b) 45000 (c) 4500
  13. 13.Best estimate of 407 + 539? (a) 700 (b) 1100 (c) 900
  14. 14.Best estimate of 17 × 23? (a) 4000 (b) 40 (c) 400
  15. 15.Best estimate of 783 + 341? (a) 1100 (b) 900 (c) 1300
  16. 16.Best estimate of 271 + 667? (a) 1200 (b) 800 (c) 1000
  17. 17.Best estimate of 546 + 697? (a) 1000 (b) 1400 (c) 1200
  18. 18.Best estimate of 43 × 84? (a) 32000 (b) 3200 (c) 320
  19. 19.Best estimate of 654 + 795? (a) 1700 (b) 1300 (c) 1500
  20. 20.Best estimate of 166 + 246? (a) 200 (b) 600 (c) 400
  21. 21.Best estimate of 836 + 173? (a) 1000 (b) 800 (c) 1200
  22. 22.Best estimate of 263 + 341? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 524 + 638? (a) 1100 (b) 1300 (c) 900
  24. 24.Best estimate of 285 + 294? (a) 400 (b) 800 (c) 600
  25. 25.Best estimate of 571 + 182? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 16 × 92? (a) 1800 (b) 180 (c) 18000
  27. 27.Best estimate of 89 × 46? (a) 45000 (b) 4500 (c) 450
  28. 28.Best estimate of 175 + 364? (a) 800 (b) 400 (c) 600
  29. 29.Best estimate of 50 × 54? (a) 2500 (b) 250 (c) 25000
  30. 30.Best estimate of 31 × 81? (a) 2400 (b) 24000 (c) 240
  31. 31.Best estimate of 253 + 370? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 20 × 76? (a) 1600 (b) 160 (c) 16000
  33. 33.Best estimate of 18 × 34? (a) 6000 (b) 600 (c) 60
  34. 34.Best estimate of 706 + 204? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 442 + 519? (a) 1100 (b) 700 (c) 900
  36. 36.Best estimate of 737 + 288? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 497 + 340? (a) 1000 (b) 600 (c) 800
  38. 38.Best estimate of 97 × 53? (a) 5000 (b) 50000 (c) 500
  39. 39.Best estimate of 89 × 93? (a) 8100 (b) 81000 (c) 810
  40. 40.Best estimate of 86 × 76? (a) 720 (b) 7200 (c) 72000

Answer key

  1. 1400
  2. 2400
  3. 1200
  4. 1600
  5. 9000
  6. 200
  7. 7200
  8. 800
  9. 1300
  10. 600
  11. 1400
  12. 4500
  13. 900
  14. 400
  15. 1100
  16. 1000
  17. 1200
  18. 3200
  19. 1500
  20. 400
  21. 1000
  22. 600
  23. 1100
  24. 600
  25. 800
  26. 1800
  27. 4500
  28. 600
  29. 2500
  30. 2400
  31. 700
  32. 1600
  33. 600
  34. 900
  35. 900
  36. 1000
  37. 800
  38. 5000
  39. 8100
  40. 7200

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