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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 497 · 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 300 + 849? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 80 × 74? (a) 5600 (b) 56000 (c) 560
  3. 3.Best estimate of 87 × 42? (a) 3600 (b) 36000 (c) 360
  4. 4.Best estimate of 602 + 405? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 31 × 63? (a) 1800 (b) 180 (c) 18000
  6. 6.Best estimate of 558 + 184? (a) 1000 (b) 800 (c) 600
  7. 7.Best estimate of 20 × 91? (a) 1800 (b) 18000 (c) 180
  8. 8.Best estimate of 141 + 841? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 38 × 33? (a) 120 (b) 1200 (c) 12000
  10. 10.Best estimate of 31 × 69? (a) 21000 (b) 2100 (c) 210
  11. 11.Best estimate of 692 + 169? (a) 700 (b) 900 (c) 1100
  12. 12.Best estimate of 16 × 14? (a) 200 (b) 20 (c) 2000
  13. 13.Best estimate of 787 + 568? (a) 1600 (b) 1200 (c) 1400
  14. 14.Best estimate of 322 + 771? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 56 × 64? (a) 36000 (b) 360 (c) 3600
  16. 16.Best estimate of 19 × 16? (a) 4000 (b) 40 (c) 400
  17. 17.Best estimate of 71 × 87? (a) 63000 (b) 630 (c) 6300
  18. 18.Best estimate of 72 × 56? (a) 4200 (b) 420 (c) 42000
  19. 19.Best estimate of 16 × 63? (a) 120 (b) 1200 (c) 12000
  20. 20.Best estimate of 60 × 13? (a) 60 (b) 600 (c) 6000
  21. 21.Best estimate of 823 + 120? (a) 1100 (b) 700 (c) 900
  22. 22.Best estimate of 813 + 610? (a) 1600 (b) 1400 (c) 1200
  23. 23.Best estimate of 218 + 828? (a) 800 (b) 1200 (c) 1000
  24. 24.Best estimate of 655 + 231? (a) 900 (b) 1100 (c) 700
  25. 25.Best estimate of 339 + 779? (a) 1100 (b) 900 (c) 1300
  26. 26.Best estimate of 46 × 42? (a) 20000 (b) 200 (c) 2000
  27. 27.Best estimate of 280 + 325? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 322 + 163? (a) 700 (b) 500 (c) 300
  29. 29.Best estimate of 569 + 288? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 527 + 312? (a) 1000 (b) 600 (c) 800
  31. 31.Best estimate of 81 × 49? (a) 400 (b) 40000 (c) 4000
  32. 32.Best estimate of 49 × 96? (a) 50000 (b) 500 (c) 5000
  33. 33.Best estimate of 346 + 280? (a) 800 (b) 600 (c) 400
  34. 34.Best estimate of 31 × 12? (a) 30 (b) 3000 (c) 300
  35. 35.Best estimate of 23 × 96? (a) 200 (b) 20000 (c) 2000
  36. 36.Best estimate of 49 × 93? (a) 45000 (b) 4500 (c) 450
  37. 37.Best estimate of 462 + 813? (a) 1300 (b) 1500 (c) 1100
  38. 38.Best estimate of 61 × 51? (a) 3000 (b) 30000 (c) 300
  39. 39.Best estimate of 274 + 666? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 92 × 92? (a) 81000 (b) 810 (c) 8100

Answer key

  1. 1100
  2. 5600
  3. 3600
  4. 1000
  5. 1800
  6. 800
  7. 1800
  8. 900
  9. 1200
  10. 2100
  11. 900
  12. 200
  13. 1400
  14. 1100
  15. 3600
  16. 400
  17. 6300
  18. 4200
  19. 1200
  20. 600
  21. 900
  22. 1400
  23. 1000
  24. 900
  25. 1100
  26. 2000
  27. 600
  28. 500
  29. 900
  30. 800
  31. 4000
  32. 5000
  33. 600
  34. 300
  35. 2000
  36. 4500
  37. 1300
  38. 3000
  39. 1000
  40. 8100

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