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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 359 · 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 23 × 62? (a) 1200 (b) 12000 (c) 120
  2. 2.Best estimate of 490 + 644? (a) 900 (b) 1300 (c) 1100
  3. 3.Best estimate of 61 × 44? (a) 2400 (b) 24000 (c) 240
  4. 4.Best estimate of 38 × 76? (a) 3200 (b) 320 (c) 32000
  5. 5.Best estimate of 36 × 32? (a) 1200 (b) 12000 (c) 120
  6. 6.Best estimate of 472 + 249? (a) 700 (b) 900 (c) 500
  7. 7.Best estimate of 706 + 160? (a) 700 (b) 900 (c) 1100
  8. 8.Best estimate of 49 × 44? (a) 200 (b) 2000 (c) 20000
  9. 9.Best estimate of 58 × 19? (a) 120 (b) 12000 (c) 1200
  10. 10.Best estimate of 36 × 47? (a) 200 (b) 2000 (c) 20000
  11. 11.Best estimate of 67 × 81? (a) 560 (b) 56000 (c) 5600
  12. 12.Best estimate of 564 + 267? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 39 × 89? (a) 36000 (b) 3600 (c) 360
  14. 14.Best estimate of 132 + 837? (a) 700 (b) 900 (c) 1100
  15. 15.Best estimate of 56 × 53? (a) 30000 (b) 300 (c) 3000
  16. 16.Best estimate of 135 + 434? (a) 700 (b) 300 (c) 500
  17. 17.Best estimate of 703 + 508? (a) 1400 (b) 1200 (c) 1000
  18. 18.Best estimate of 58 × 34? (a) 1800 (b) 18000 (c) 180
  19. 19.Best estimate of 86 × 53? (a) 4500 (b) 450 (c) 45000
  20. 20.Best estimate of 88 × 81? (a) 720 (b) 7200 (c) 72000
  21. 21.Best estimate of 232 + 352? (a) 600 (b) 400 (c) 800
  22. 22.Best estimate of 46 × 18? (a) 100 (b) 10000 (c) 1000
  23. 23.Best estimate of 13 × 84? (a) 8000 (b) 80 (c) 800
  24. 24.Best estimate of 585 + 323? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 58 × 47? (a) 3000 (b) 30000 (c) 300
  26. 26.Best estimate of 90 × 86? (a) 81000 (b) 810 (c) 8100
  27. 27.Best estimate of 38 × 71? (a) 2800 (b) 280 (c) 28000
  28. 28.Best estimate of 543 + 196? (a) 500 (b) 900 (c) 700
  29. 29.Best estimate of 36 × 56? (a) 24000 (b) 2400 (c) 240
  30. 30.Best estimate of 64 × 26? (a) 1800 (b) 180 (c) 18000
  31. 31.Best estimate of 47 × 90? (a) 4500 (b) 45000 (c) 450
  32. 32.Best estimate of 98 × 76? (a) 800 (b) 8000 (c) 80000
  33. 33.Best estimate of 435 + 157? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 37 × 81? (a) 320 (b) 3200 (c) 32000
  35. 35.Best estimate of 155 + 363? (a) 800 (b) 400 (c) 600
  36. 36.Best estimate of 81 × 31? (a) 2400 (b) 24000 (c) 240
  37. 37.Best estimate of 62 × 36? (a) 24000 (b) 240 (c) 2400
  38. 38.Best estimate of 26 × 16? (a) 600 (b) 60 (c) 6000
  39. 39.Best estimate of 862 + 694? (a) 1800 (b) 1400 (c) 1600
  40. 40.Best estimate of 766 + 251? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 1200
  2. 1100
  3. 2400
  4. 3200
  5. 1200
  6. 700
  7. 900
  8. 2000
  9. 1200
  10. 2000
  11. 5600
  12. 900
  13. 3600
  14. 900
  15. 3000
  16. 500
  17. 1200
  18. 1800
  19. 4500
  20. 7200
  21. 600
  22. 1000
  23. 800
  24. 900
  25. 3000
  26. 8100
  27. 2800
  28. 700
  29. 2400
  30. 1800
  31. 4500
  32. 8000
  33. 600
  34. 3200
  35. 600
  36. 2400
  37. 2400
  38. 600
  39. 1600
  40. 1100

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