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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 14 · 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 461 + 615? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 58 × 14? (a) 600 (b) 6000 (c) 60
  3. 3.Best estimate of 64 × 96? (a) 6000 (b) 60000 (c) 600
  4. 4.Best estimate of 73 × 50? (a) 35000 (b) 3500 (c) 350
  5. 5.Best estimate of 20 × 44? (a) 8000 (b) 80 (c) 800
  6. 6.Best estimate of 64 × 84? (a) 48000 (b) 480 (c) 4800
  7. 7.Best estimate of 87 × 12? (a) 900 (b) 9000 (c) 90
  8. 8.Best estimate of 86 × 93? (a) 8100 (b) 81000 (c) 810
  9. 9.Best estimate of 313 + 774? (a) 900 (b) 1100 (c) 1300
  10. 10.Best estimate of 23 × 86? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 94 × 71? (a) 6300 (b) 63000 (c) 630
  12. 12.Best estimate of 317 + 329? (a) 600 (b) 400 (c) 800
  13. 13.Best estimate of 185 + 201? (a) 400 (b) 200 (c) 600
  14. 14.Best estimate of 263 + 743? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 26 × 26? (a) 9000 (b) 90 (c) 900
  16. 16.Best estimate of 84 × 40? (a) 320 (b) 32000 (c) 3200
  17. 17.Best estimate of 132 + 430? (a) 500 (b) 300 (c) 700
  18. 18.Best estimate of 96 × 16? (a) 200 (b) 2000 (c) 20000
  19. 19.Best estimate of 42 × 68? (a) 280 (b) 2800 (c) 28000
  20. 20.Best estimate of 578 + 430? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 53 × 74? (a) 350 (b) 3500 (c) 35000
  22. 22.Best estimate of 293 + 338? (a) 600 (b) 800 (c) 400
  23. 23.Best estimate of 37 × 19? (a) 80 (b) 8000 (c) 800
  24. 24.Best estimate of 86 × 47? (a) 450 (b) 45000 (c) 4500
  25. 25.Best estimate of 144 + 783? (a) 900 (b) 1100 (c) 700
  26. 26.Best estimate of 74 × 73? (a) 4900 (b) 49000 (c) 490
  27. 27.Best estimate of 168 + 677? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 53 × 16? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 86 × 53? (a) 450 (b) 45000 (c) 4500
  30. 30.Best estimate of 452 + 643? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 58 × 68? (a) 4200 (b) 42000 (c) 420
  32. 32.Best estimate of 76 × 20? (a) 160 (b) 16000 (c) 1600
  33. 33.Best estimate of 73 × 71? (a) 49000 (b) 4900 (c) 490
  34. 34.Best estimate of 66 × 18? (a) 14000 (b) 140 (c) 1400
  35. 35.Best estimate of 73 × 72? (a) 4900 (b) 490 (c) 49000
  36. 36.Best estimate of 165 + 275? (a) 700 (b) 300 (c) 500
  37. 37.Best estimate of 94 × 94? (a) 810 (b) 8100 (c) 81000
  38. 38.Best estimate of 61 × 67? (a) 420 (b) 42000 (c) 4200
  39. 39.Best estimate of 59 × 43? (a) 24000 (b) 2400 (c) 240
  40. 40.Best estimate of 243 + 320? (a) 300 (b) 700 (c) 500

Answer key

  1. 1100
  2. 600
  3. 6000
  4. 3500
  5. 800
  6. 4800
  7. 900
  8. 8100
  9. 1100
  10. 1800
  11. 6300
  12. 600
  13. 400
  14. 1000
  15. 900
  16. 3200
  17. 500
  18. 2000
  19. 2800
  20. 1000
  21. 3500
  22. 600
  23. 800
  24. 4500
  25. 900
  26. 4900
  27. 900
  28. 1000
  29. 4500
  30. 1100
  31. 4200
  32. 1600
  33. 4900
  34. 1400
  35. 4900
  36. 500
  37. 8100
  38. 4200
  39. 2400
  40. 500

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