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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 780 · 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 286 + 199? (a) 700 (b) 300 (c) 500
  2. 2.Best estimate of 52 × 98? (a) 5000 (b) 500 (c) 50000
  3. 3.Best estimate of 160 + 755? (a) 1200 (b) 1000 (c) 800
  4. 4.Best estimate of 358 + 677? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 148 + 858? (a) 1200 (b) 800 (c) 1000
  6. 6.Best estimate of 63 × 69? (a) 4200 (b) 42000 (c) 420
  7. 7.Best estimate of 46 × 18? (a) 10000 (b) 100 (c) 1000
  8. 8.Best estimate of 18 × 60? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 24 × 80? (a) 1600 (b) 16000 (c) 160
  10. 10.Best estimate of 620 + 656? (a) 1500 (b) 1300 (c) 1100
  11. 11.Best estimate of 18 × 58? (a) 12000 (b) 120 (c) 1200
  12. 12.Best estimate of 57 × 16? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 215 + 391? (a) 600 (b) 400 (c) 800
  14. 14.Best estimate of 72 × 83? (a) 5600 (b) 560 (c) 56000
  15. 15.Best estimate of 63 × 36? (a) 2400 (b) 24000 (c) 240
  16. 16.Best estimate of 39 × 90? (a) 3600 (b) 36000 (c) 360
  17. 17.Best estimate of 46 × 22? (a) 1000 (b) 100 (c) 10000
  18. 18.Best estimate of 402 + 658? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 97 × 21? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 46 × 26? (a) 15000 (b) 1500 (c) 150
  21. 21.Best estimate of 249 + 200? (a) 400 (b) 200 (c) 600
  22. 22.Best estimate of 880 + 138? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 79 × 62? (a) 4800 (b) 48000 (c) 480
  24. 24.Best estimate of 76 × 27? (a) 2400 (b) 240 (c) 24000
  25. 25.Best estimate of 86 × 22? (a) 180 (b) 18000 (c) 1800
  26. 26.Best estimate of 19 × 31? (a) 60 (b) 600 (c) 6000
  27. 27.Best estimate of 86 × 54? (a) 450 (b) 4500 (c) 45000
  28. 28.Best estimate of 48 × 29? (a) 1500 (b) 150 (c) 15000
  29. 29.Best estimate of 94 × 87? (a) 81000 (b) 8100 (c) 810
  30. 30.Best estimate of 351 + 278? (a) 900 (b) 700 (c) 500
  31. 31.Best estimate of 66 × 56? (a) 420 (b) 4200 (c) 42000
  32. 32.Best estimate of 92 × 66? (a) 6300 (b) 630 (c) 63000
  33. 33.Best estimate of 800 + 717? (a) 1300 (b) 1500 (c) 1700
  34. 34.Best estimate of 259 + 754? (a) 1100 (b) 1300 (c) 900
  35. 35.Best estimate of 326 + 252? (a) 400 (b) 600 (c) 800
  36. 36.Best estimate of 68 × 16? (a) 140 (b) 1400 (c) 14000
  37. 37.Best estimate of 36 × 34? (a) 12000 (b) 1200 (c) 120
  38. 38.Best estimate of 92 × 17? (a) 1800 (b) 180 (c) 18000
  39. 39.Best estimate of 477 + 494? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 254 + 548? (a) 600 (b) 800 (c) 1000

Answer key

  1. 500
  2. 5000
  3. 1000
  4. 1100
  5. 1000
  6. 4200
  7. 1000
  8. 1200
  9. 1600
  10. 1300
  11. 1200
  12. 1200
  13. 600
  14. 5600
  15. 2400
  16. 3600
  17. 1000
  18. 1100
  19. 2000
  20. 1500
  21. 400
  22. 1000
  23. 4800
  24. 2400
  25. 1800
  26. 600
  27. 4500
  28. 1500
  29. 8100
  30. 700
  31. 4200
  32. 6300
  33. 1500
  34. 1100
  35. 600
  36. 1400
  37. 1200
  38. 1800
  39. 1000
  40. 800

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