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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 718 · 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 26 × 76? (a) 24000 (b) 2400 (c) 240
  2. 2.Best estimate of 52 × 64? (a) 300 (b) 30000 (c) 3000
  3. 3.Best estimate of 23 × 96? (a) 20000 (b) 2000 (c) 200
  4. 4.Best estimate of 69 × 96? (a) 70000 (b) 700 (c) 7000
  5. 5.Best estimate of 20 × 62? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 58 × 21? (a) 12000 (b) 1200 (c) 120
  7. 7.Best estimate of 20 × 37? (a) 800 (b) 80 (c) 8000
  8. 8.Best estimate of 740 + 728? (a) 1600 (b) 1400 (c) 1200
  9. 9.Best estimate of 212 + 189? (a) 600 (b) 400 (c) 200
  10. 10.Best estimate of 192 + 340? (a) 700 (b) 500 (c) 300
  11. 11.Best estimate of 514 + 867? (a) 1600 (b) 1400 (c) 1200
  12. 12.Best estimate of 16 × 91? (a) 18000 (b) 180 (c) 1800
  13. 13.Best estimate of 862 + 869? (a) 1800 (b) 1600 (c) 2000
  14. 14.Best estimate of 771 + 130? (a) 900 (b) 700 (c) 1100
  15. 15.Best estimate of 31 × 44? (a) 1200 (b) 120 (c) 12000
  16. 16.Best estimate of 62 × 17? (a) 120 (b) 1200 (c) 12000
  17. 17.Best estimate of 40 × 86? (a) 360 (b) 36000 (c) 3600
  18. 18.Best estimate of 763 + 293? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 180 + 245? (a) 400 (b) 200 (c) 600
  20. 20.Best estimate of 581 + 222? (a) 600 (b) 800 (c) 1000
  21. 21.Best estimate of 77 × 56? (a) 480 (b) 4800 (c) 48000
  22. 22.Best estimate of 62 × 42? (a) 24000 (b) 2400 (c) 240
  23. 23.Best estimate of 87 × 28? (a) 27000 (b) 270 (c) 2700
  24. 24.Best estimate of 84 × 77? (a) 640 (b) 6400 (c) 64000
  25. 25.Best estimate of 623 + 252? (a) 900 (b) 700 (c) 1100
  26. 26.Best estimate of 96 × 48? (a) 500 (b) 5000 (c) 50000
  27. 27.Best estimate of 824 + 156? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 47 × 81? (a) 4000 (b) 40000 (c) 400
  29. 29.Best estimate of 92 × 48? (a) 4500 (b) 450 (c) 45000
  30. 30.Best estimate of 461 + 805? (a) 1100 (b) 1500 (c) 1300
  31. 31.Best estimate of 69 × 13? (a) 7000 (b) 700 (c) 70
  32. 32.Best estimate of 802 + 517? (a) 1300 (b) 1100 (c) 1500
  33. 33.Best estimate of 86 × 89? (a) 81000 (b) 810 (c) 8100
  34. 34.Best estimate of 364 + 554? (a) 800 (b) 1000 (c) 1200
  35. 35.Best estimate of 66 × 33? (a) 21000 (b) 210 (c) 2100
  36. 36.Best estimate of 416 + 122? (a) 500 (b) 700 (c) 300
  37. 37.Best estimate of 12 × 96? (a) 1000 (b) 100 (c) 10000
  38. 38.Best estimate of 22 × 81? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 414 + 776? (a) 1200 (b) 1000 (c) 1400
  40. 40.Best estimate of 577 + 281? (a) 1100 (b) 900 (c) 700

Answer key

  1. 2400
  2. 3000
  3. 2000
  4. 7000
  5. 1200
  6. 1200
  7. 800
  8. 1400
  9. 400
  10. 500
  11. 1400
  12. 1800
  13. 1800
  14. 900
  15. 1200
  16. 1200
  17. 3600
  18. 1100
  19. 400
  20. 800
  21. 4800
  22. 2400
  23. 2700
  24. 6400
  25. 900
  26. 5000
  27. 1000
  28. 4000
  29. 4500
  30. 1300
  31. 700
  32. 1300
  33. 8100
  34. 1000
  35. 2100
  36. 500
  37. 1000
  38. 1600
  39. 1200
  40. 900

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