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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 245 · 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 43 × 28? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 64 × 84? (a) 48000 (b) 480 (c) 4800
  3. 3.Best estimate of 74 × 34? (a) 21000 (b) 210 (c) 2100
  4. 4.Best estimate of 98 × 92? (a) 9000 (b) 90000 (c) 900
  5. 5.Best estimate of 82 × 24? (a) 1600 (b) 16000 (c) 160
  6. 6.Best estimate of 13 × 56? (a) 60 (b) 600 (c) 6000
  7. 7.Best estimate of 19 × 22? (a) 40 (b) 4000 (c) 400
  8. 8.Best estimate of 31 × 97? (a) 3000 (b) 300 (c) 30000
  9. 9.Best estimate of 40 × 56? (a) 2400 (b) 240 (c) 24000
  10. 10.Best estimate of 21 × 13? (a) 2000 (b) 20 (c) 200
  11. 11.Best estimate of 243 + 321? (a) 300 (b) 500 (c) 700
  12. 12.Best estimate of 72 × 39? (a) 280 (b) 28000 (c) 2800
  13. 13.Best estimate of 479 + 865? (a) 1600 (b) 1400 (c) 1200
  14. 14.Best estimate of 40 × 84? (a) 320 (b) 3200 (c) 32000
  15. 15.Best estimate of 51 × 57? (a) 300 (b) 30000 (c) 3000
  16. 16.Best estimate of 733 + 454? (a) 1000 (b) 1400 (c) 1200
  17. 17.Best estimate of 551 + 163? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 134 + 325? (a) 200 (b) 600 (c) 400
  19. 19.Best estimate of 325 + 557? (a) 900 (b) 1100 (c) 700
  20. 20.Best estimate of 94 × 46? (a) 45000 (b) 4500 (c) 450
  21. 21.Best estimate of 687 + 834? (a) 1700 (b) 1500 (c) 1300
  22. 22.Best estimate of 31 × 86? (a) 2700 (b) 270 (c) 27000
  23. 23.Best estimate of 762 + 469? (a) 1100 (b) 1300 (c) 1500
  24. 24.Best estimate of 316 + 686? (a) 800 (b) 1200 (c) 1000
  25. 25.Best estimate of 592 + 416? (a) 1000 (b) 1200 (c) 800
  26. 26.Best estimate of 782 + 343? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 40 × 83? (a) 32000 (b) 320 (c) 3200
  28. 28.Best estimate of 58 × 73? (a) 4200 (b) 420 (c) 42000
  29. 29.Best estimate of 601 + 497? (a) 1300 (b) 1100 (c) 900
  30. 30.Best estimate of 49 × 49? (a) 250 (b) 2500 (c) 25000
  31. 31.Best estimate of 70 × 62? (a) 42000 (b) 4200 (c) 420
  32. 32.Best estimate of 300 + 720? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 87 × 96? (a) 900 (b) 90000 (c) 9000
  34. 34.Best estimate of 842 + 634? (a) 1200 (b) 1400 (c) 1600
  35. 35.Best estimate of 32 × 13? (a) 30 (b) 300 (c) 3000
  36. 36.Best estimate of 69 × 36? (a) 280 (b) 2800 (c) 28000
  37. 37.Best estimate of 92 × 17? (a) 1800 (b) 18000 (c) 180
  38. 38.Best estimate of 43 × 74? (a) 280 (b) 2800 (c) 28000
  39. 39.Best estimate of 66 × 41? (a) 28000 (b) 2800 (c) 280
  40. 40.Best estimate of 17 × 71? (a) 1400 (b) 140 (c) 14000

Answer key

  1. 1200
  2. 4800
  3. 2100
  4. 9000
  5. 1600
  6. 600
  7. 400
  8. 3000
  9. 2400
  10. 200
  11. 500
  12. 2800
  13. 1400
  14. 3200
  15. 3000
  16. 1200
  17. 800
  18. 400
  19. 900
  20. 4500
  21. 1500
  22. 2700
  23. 1300
  24. 1000
  25. 1000
  26. 1100
  27. 3200
  28. 4200
  29. 1100
  30. 2500
  31. 4200
  32. 1000
  33. 9000
  34. 1400
  35. 300
  36. 2800
  37. 1800
  38. 2800
  39. 2800
  40. 1400

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