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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 38 · 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 46 × 26? (a) 15000 (b) 150 (c) 1500
  2. 2.Best estimate of 29 × 16? (a) 6000 (b) 60 (c) 600
  3. 3.Best estimate of 81 × 69? (a) 5600 (b) 56000 (c) 560
  4. 4.Best estimate of 237 + 546? (a) 500 (b) 700 (c) 900
  5. 5.Best estimate of 90 × 38? (a) 3600 (b) 36000 (c) 360
  6. 6.Best estimate of 22 × 22? (a) 40 (b) 4000 (c) 400
  7. 7.Best estimate of 624 + 301? (a) 1100 (b) 900 (c) 700
  8. 8.Best estimate of 36 × 14? (a) 40 (b) 4000 (c) 400
  9. 9.Best estimate of 727 + 326? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 46 × 76? (a) 4000 (b) 40000 (c) 400
  11. 11.Best estimate of 295 + 203? (a) 300 (b) 500 (c) 700
  12. 12.Best estimate of 32 × 72? (a) 2100 (b) 210 (c) 21000
  13. 13.Best estimate of 22 × 32? (a) 600 (b) 60 (c) 6000
  14. 14.Best estimate of 754 + 813? (a) 1400 (b) 1800 (c) 1600
  15. 15.Best estimate of 92 × 52? (a) 45000 (b) 4500 (c) 450
  16. 16.Best estimate of 158 + 461? (a) 700 (b) 500 (c) 900
  17. 17.Best estimate of 582 + 627? (a) 1000 (b) 1400 (c) 1200
  18. 18.Best estimate of 18 × 90? (a) 180 (b) 18000 (c) 1800
  19. 19.Best estimate of 17 × 69? (a) 140 (b) 14000 (c) 1400
  20. 20.Best estimate of 179 + 582? (a) 1000 (b) 600 (c) 800
  21. 21.Best estimate of 208 + 426? (a) 400 (b) 800 (c) 600
  22. 22.Best estimate of 66 × 50? (a) 3500 (b) 35000 (c) 350
  23. 23.Best estimate of 359 + 214? (a) 400 (b) 600 (c) 800
  24. 24.Best estimate of 40 × 34? (a) 12000 (b) 1200 (c) 120
  25. 25.Best estimate of 64 × 78? (a) 48000 (b) 480 (c) 4800
  26. 26.Best estimate of 32 × 62? (a) 18000 (b) 1800 (c) 180
  27. 27.Best estimate of 31 × 93? (a) 2700 (b) 27000 (c) 270
  28. 28.Best estimate of 62 × 41? (a) 24000 (b) 240 (c) 2400
  29. 29.Best estimate of 127 + 833? (a) 1100 (b) 900 (c) 700
  30. 30.Best estimate of 52 × 69? (a) 350 (b) 3500 (c) 35000
  31. 31.Best estimate of 49 × 72? (a) 3500 (b) 350 (c) 35000
  32. 32.Best estimate of 833 + 556? (a) 1600 (b) 1200 (c) 1400
  33. 33.Best estimate of 388 + 242? (a) 600 (b) 400 (c) 800
  34. 34.Best estimate of 56 × 42? (a) 2400 (b) 240 (c) 24000
  35. 35.Best estimate of 78 × 69? (a) 5600 (b) 56000 (c) 560
  36. 36.Best estimate of 563 + 138? (a) 700 (b) 500 (c) 900
  37. 37.Best estimate of 91 × 16? (a) 1800 (b) 180 (c) 18000
  38. 38.Best estimate of 193 + 644? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 147 + 428? (a) 700 (b) 300 (c) 500
  40. 40.Best estimate of 78 × 22? (a) 16000 (b) 160 (c) 1600

Answer key

  1. 1500
  2. 600
  3. 5600
  4. 700
  5. 3600
  6. 400
  7. 900
  8. 400
  9. 1000
  10. 4000
  11. 500
  12. 2100
  13. 600
  14. 1600
  15. 4500
  16. 700
  17. 1200
  18. 1800
  19. 1400
  20. 800
  21. 600
  22. 3500
  23. 600
  24. 1200
  25. 4800
  26. 1800
  27. 2700
  28. 2400
  29. 900
  30. 3500
  31. 3500
  32. 1400
  33. 600
  34. 2400
  35. 5600
  36. 700
  37. 1800
  38. 800
  39. 500
  40. 1600

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