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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 96 · 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 22 × 79? (a) 1600 (b) 160 (c) 16000
  2. 2.Best estimate of 871 + 307? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 28 × 67? (a) 2100 (b) 210 (c) 21000
  4. 4.Best estimate of 67 × 71? (a) 49000 (b) 4900 (c) 490
  5. 5.Best estimate of 26 × 52? (a) 1500 (b) 15000 (c) 150
  6. 6.Best estimate of 468 + 149? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 36 × 38? (a) 1600 (b) 16000 (c) 160
  8. 8.Best estimate of 830 + 391? (a) 1400 (b) 1000 (c) 1200
  9. 9.Best estimate of 16 × 27? (a) 600 (b) 6000 (c) 60
  10. 10.Best estimate of 36 × 63? (a) 24000 (b) 2400 (c) 240
  11. 11.Best estimate of 596 + 548? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 23 × 92? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 431 + 516? (a) 900 (b) 700 (c) 1100
  14. 14.Best estimate of 23 × 93? (a) 18000 (b) 1800 (c) 180
  15. 15.Best estimate of 76 × 90? (a) 72000 (b) 720 (c) 7200
  16. 16.Best estimate of 506 + 822? (a) 1100 (b) 1500 (c) 1300
  17. 17.Best estimate of 34 × 17? (a) 600 (b) 6000 (c) 60
  18. 18.Best estimate of 598 + 680? (a) 1500 (b) 1100 (c) 1300
  19. 19.Best estimate of 807 + 242? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 151 + 524? (a) 500 (b) 900 (c) 700
  21. 21.Best estimate of 125 + 413? (a) 300 (b) 700 (c) 500
  22. 22.Best estimate of 717 + 484? (a) 1000 (b) 1200 (c) 1400
  23. 23.Best estimate of 18 × 86? (a) 18000 (b) 1800 (c) 180
  24. 24.Best estimate of 829 + 403? (a) 1200 (b) 1000 (c) 1400
  25. 25.Best estimate of 448 + 401? (a) 800 (b) 600 (c) 1000
  26. 26.Best estimate of 368 + 432? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 98 × 37? (a) 400 (b) 40000 (c) 4000
  28. 28.Best estimate of 66 × 57? (a) 42000 (b) 4200 (c) 420
  29. 29.Best estimate of 430 + 418? (a) 800 (b) 600 (c) 1000
  30. 30.Best estimate of 323 + 441? (a) 700 (b) 500 (c) 900
  31. 31.Best estimate of 234 + 460? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 38 × 14? (a) 40 (b) 4000 (c) 400
  33. 33.Best estimate of 633 + 373? (a) 800 (b) 1200 (c) 1000
  34. 34.Best estimate of 257 + 337? (a) 800 (b) 400 (c) 600
  35. 35.Best estimate of 68 × 72? (a) 49000 (b) 4900 (c) 490
  36. 36.Best estimate of 626 + 805? (a) 1600 (b) 1400 (c) 1200
  37. 37.Best estimate of 157 + 719? (a) 700 (b) 1100 (c) 900
  38. 38.Best estimate of 43 × 79? (a) 32000 (b) 320 (c) 3200
  39. 39.Best estimate of 823 + 653? (a) 1500 (b) 1700 (c) 1300
  40. 40.Best estimate of 302 + 224? (a) 300 (b) 700 (c) 500

Answer key

  1. 1600
  2. 1200
  3. 2100
  4. 4900
  5. 1500
  6. 600
  7. 1600
  8. 1200
  9. 600
  10. 2400
  11. 1100
  12. 1800
  13. 900
  14. 1800
  15. 7200
  16. 1300
  17. 600
  18. 1300
  19. 1000
  20. 700
  21. 500
  22. 1200
  23. 1800
  24. 1200
  25. 800
  26. 800
  27. 4000
  28. 4200
  29. 800
  30. 700
  31. 700
  32. 400
  33. 1000
  34. 600
  35. 4900
  36. 1400
  37. 900
  38. 3200
  39. 1500
  40. 500

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