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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 675 · 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 57 × 71? (a) 420 (b) 4200 (c) 42000
  2. 2.Best estimate of 92 × 96? (a) 9000 (b) 90000 (c) 900
  3. 3.Best estimate of 156 + 331? (a) 300 (b) 500 (c) 700
  4. 4.Best estimate of 84 × 44? (a) 3200 (b) 32000 (c) 320
  5. 5.Best estimate of 64 × 76? (a) 48000 (b) 4800 (c) 480
  6. 6.Best estimate of 36 × 28? (a) 120 (b) 1200 (c) 12000
  7. 7.Best estimate of 91 × 92? (a) 810 (b) 8100 (c) 81000
  8. 8.Best estimate of 56 × 16? (a) 12000 (b) 120 (c) 1200
  9. 9.Best estimate of 51 × 66? (a) 350 (b) 3500 (c) 35000
  10. 10.Best estimate of 404 + 608? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 13 × 31? (a) 30 (b) 300 (c) 3000
  12. 12.Best estimate of 297 + 839? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 231 + 660? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 12 × 53? (a) 500 (b) 50 (c) 5000
  15. 15.Best estimate of 77 × 26? (a) 2400 (b) 24000 (c) 240
  16. 16.Best estimate of 38 × 28? (a) 120 (b) 12000 (c) 1200
  17. 17.Best estimate of 592 + 251? (a) 1100 (b) 900 (c) 700
  18. 18.Best estimate of 40 × 56? (a) 240 (b) 24000 (c) 2400
  19. 19.Best estimate of 86 × 79? (a) 72000 (b) 720 (c) 7200
  20. 20.Best estimate of 373 + 841? (a) 1000 (b) 1200 (c) 1400
  21. 21.Best estimate of 610 + 431? (a) 1000 (b) 800 (c) 1200
  22. 22.Best estimate of 253 + 771? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 767 + 192? (a) 1000 (b) 1200 (c) 800
  24. 24.Best estimate of 815 + 154? (a) 1200 (b) 800 (c) 1000
  25. 25.Best estimate of 245 + 176? (a) 400 (b) 600 (c) 200
  26. 26.Best estimate of 405 + 355? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 416 + 172? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 668 + 301? (a) 800 (b) 1000 (c) 1200
  29. 29.Best estimate of 20 × 34? (a) 6000 (b) 60 (c) 600
  30. 30.Best estimate of 719 + 678? (a) 1400 (b) 1600 (c) 1200
  31. 31.Best estimate of 773 + 811? (a) 1800 (b) 1600 (c) 1400
  32. 32.Best estimate of 23 × 32? (a) 6000 (b) 600 (c) 60
  33. 33.Best estimate of 614 + 629? (a) 1000 (b) 1400 (c) 1200
  34. 34.Best estimate of 244 + 252? (a) 700 (b) 500 (c) 300
  35. 35.Best estimate of 281 + 795? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 83 × 66? (a) 56000 (b) 560 (c) 5600
  37. 37.Best estimate of 712 + 299? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 232 + 244? (a) 400 (b) 600 (c) 200
  39. 39.Best estimate of 82 × 32? (a) 2400 (b) 24000 (c) 240
  40. 40.Best estimate of 140 + 608? (a) 700 (b) 500 (c) 900

Answer key

  1. 4200
  2. 9000
  3. 500
  4. 3200
  5. 4800
  6. 1200
  7. 8100
  8. 1200
  9. 3500
  10. 1000
  11. 300
  12. 1100
  13. 900
  14. 500
  15. 2400
  16. 1200
  17. 900
  18. 2400
  19. 7200
  20. 1200
  21. 1000
  22. 1100
  23. 1000
  24. 1000
  25. 400
  26. 800
  27. 600
  28. 1000
  29. 600
  30. 1400
  31. 1600
  32. 600
  33. 1200
  34. 500
  35. 1100
  36. 5600
  37. 1000
  38. 400
  39. 2400
  40. 700

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