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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 550 · 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 137 + 501? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 92 × 26? (a) 27000 (b) 2700 (c) 270
  3. 3.Best estimate of 12 × 61? (a) 600 (b) 60 (c) 6000
  4. 4.Best estimate of 34 × 61? (a) 18000 (b) 1800 (c) 180
  5. 5.Best estimate of 524 + 716? (a) 1000 (b) 1200 (c) 1400
  6. 6.Best estimate of 185 + 372? (a) 800 (b) 600 (c) 400
  7. 7.Best estimate of 61 × 61? (a) 360 (b) 3600 (c) 36000
  8. 8.Best estimate of 78 × 26? (a) 2400 (b) 24000 (c) 240
  9. 9.Best estimate of 37 × 13? (a) 40 (b) 400 (c) 4000
  10. 10.Best estimate of 77 × 36? (a) 3200 (b) 320 (c) 32000
  11. 11.Best estimate of 19 × 84? (a) 1600 (b) 160 (c) 16000
  12. 12.Best estimate of 84 × 86? (a) 7200 (b) 72000 (c) 720
  13. 13.Best estimate of 330 + 151? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 40 × 34? (a) 1200 (b) 12000 (c) 120
  15. 15.Best estimate of 92 × 66? (a) 630 (b) 6300 (c) 63000
  16. 16.Best estimate of 56 × 51? (a) 300 (b) 3000 (c) 30000
  17. 17.Best estimate of 53 × 22? (a) 10000 (b) 1000 (c) 100
  18. 18.Best estimate of 24 × 40? (a) 8000 (b) 80 (c) 800
  19. 19.Best estimate of 674 + 865? (a) 1600 (b) 1400 (c) 1800
  20. 20.Best estimate of 93 × 53? (a) 4500 (b) 450 (c) 45000
  21. 21.Best estimate of 777 + 618? (a) 1400 (b) 1200 (c) 1600
  22. 22.Best estimate of 56 × 26? (a) 18000 (b) 180 (c) 1800
  23. 23.Best estimate of 84 × 46? (a) 4000 (b) 40000 (c) 400
  24. 24.Best estimate of 875 + 616? (a) 1300 (b) 1500 (c) 1700
  25. 25.Best estimate of 72 × 57? (a) 4200 (b) 420 (c) 42000
  26. 26.Best estimate of 190 + 684? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 282 + 643? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 91 × 90? (a) 810 (b) 8100 (c) 81000
  29. 29.Best estimate of 46 × 81? (a) 4000 (b) 40000 (c) 400
  30. 30.Best estimate of 70 × 96? (a) 70000 (b) 7000 (c) 700
  31. 31.Best estimate of 52 × 41? (a) 200 (b) 20000 (c) 2000
  32. 32.Best estimate of 219 + 663? (a) 700 (b) 900 (c) 1100
  33. 33.Best estimate of 712 + 797? (a) 1700 (b) 1500 (c) 1300
  34. 34.Best estimate of 559 + 302? (a) 1100 (b) 700 (c) 900
  35. 35.Best estimate of 328 + 707? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 639 + 476? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 86 × 41? (a) 36000 (b) 360 (c) 3600
  38. 38.Best estimate of 67 × 97? (a) 7000 (b) 700 (c) 70000
  39. 39.Best estimate of 355 + 813? (a) 1000 (b) 1200 (c) 1400
  40. 40.Best estimate of 46 × 36? (a) 2000 (b) 200 (c) 20000

Answer key

  1. 600
  2. 2700
  3. 600
  4. 1800
  5. 1200
  6. 600
  7. 3600
  8. 2400
  9. 400
  10. 3200
  11. 1600
  12. 7200
  13. 500
  14. 1200
  15. 6300
  16. 3000
  17. 1000
  18. 800
  19. 1600
  20. 4500
  21. 1400
  22. 1800
  23. 4000
  24. 1500
  25. 4200
  26. 900
  27. 900
  28. 8100
  29. 4000
  30. 7000
  31. 2000
  32. 900
  33. 1500
  34. 900
  35. 1000
  36. 1100
  37. 3600
  38. 7000
  39. 1200
  40. 2000

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