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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 839 · 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 96 × 86? (a) 9000 (b) 90000 (c) 900
  2. 2.Best estimate of 19 × 61? (a) 1200 (b) 12000 (c) 120
  3. 3.Best estimate of 157 + 562? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 216 + 868? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 661 + 858? (a) 1400 (b) 1600 (c) 1800
  6. 6.Best estimate of 80 × 31? (a) 2400 (b) 240 (c) 24000
  7. 7.Best estimate of 66 × 93? (a) 63000 (b) 6300 (c) 630
  8. 8.Best estimate of 16 × 34? (a) 60 (b) 6000 (c) 600
  9. 9.Best estimate of 492 + 443? (a) 1100 (b) 700 (c) 900
  10. 10.Best estimate of 152 + 164? (a) 400 (b) 600 (c) 200
  11. 11.Best estimate of 36 × 62? (a) 24000 (b) 2400 (c) 240
  12. 12.Best estimate of 67 × 60? (a) 42000 (b) 4200 (c) 420
  13. 13.Best estimate of 136 + 375? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 192 + 254? (a) 300 (b) 700 (c) 500
  15. 15.Best estimate of 71 × 46? (a) 3500 (b) 350 (c) 35000
  16. 16.Best estimate of 287 + 663? (a) 800 (b) 1000 (c) 1200
  17. 17.Best estimate of 295 + 367? (a) 900 (b) 700 (c) 500
  18. 18.Best estimate of 128 + 874? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 88 × 98? (a) 90000 (b) 900 (c) 9000
  20. 20.Best estimate of 28 × 66? (a) 210 (b) 2100 (c) 21000
  21. 21.Best estimate of 17 × 51? (a) 10000 (b) 100 (c) 1000
  22. 22.Best estimate of 14 × 91? (a) 900 (b) 90 (c) 9000
  23. 23.Best estimate of 225 + 171? (a) 400 (b) 600 (c) 200
  24. 24.Best estimate of 31 × 70? (a) 210 (b) 2100 (c) 21000
  25. 25.Best estimate of 151 + 797? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 42 × 98? (a) 4000 (b) 400 (c) 40000
  27. 27.Best estimate of 364 + 153? (a) 800 (b) 400 (c) 600
  28. 28.Best estimate of 82 × 61? (a) 4800 (b) 480 (c) 48000
  29. 29.Best estimate of 56 × 22? (a) 12000 (b) 1200 (c) 120
  30. 30.Best estimate of 63 × 26? (a) 1800 (b) 18000 (c) 180
  31. 31.Best estimate of 91 × 30? (a) 27000 (b) 270 (c) 2700
  32. 32.Best estimate of 170 + 811? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 12 × 52? (a) 5000 (b) 500 (c) 50
  34. 34.Best estimate of 330 + 665? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 84 × 69? (a) 56000 (b) 5600 (c) 560
  36. 36.Best estimate of 53 × 83? (a) 4000 (b) 40000 (c) 400
  37. 37.Best estimate of 328 + 321? (a) 400 (b) 800 (c) 600
  38. 38.Best estimate of 500 + 627? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 348 + 203? (a) 300 (b) 500 (c) 700
  40. 40.Best estimate of 97 × 16? (a) 20000 (b) 2000 (c) 200

Answer key

  1. 9000
  2. 1200
  3. 800
  4. 1100
  5. 1600
  6. 2400
  7. 6300
  8. 600
  9. 900
  10. 400
  11. 2400
  12. 4200
  13. 500
  14. 500
  15. 3500
  16. 1000
  17. 700
  18. 1000
  19. 9000
  20. 2100
  21. 1000
  22. 900
  23. 400
  24. 2100
  25. 1000
  26. 4000
  27. 600
  28. 4800
  29. 1200
  30. 1800
  31. 2700
  32. 1000
  33. 500
  34. 1000
  35. 5600
  36. 4000
  37. 600
  38. 1100
  39. 500
  40. 2000

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