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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 969 · 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 47 × 46? (a) 25000 (b) 2500 (c) 250
  2. 2.Best estimate of 98 × 71? (a) 700 (b) 70000 (c) 7000
  3. 3.Best estimate of 655 + 269? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 823 + 134? (a) 900 (b) 700 (c) 1100
  5. 5.Best estimate of 186 + 236? (a) 600 (b) 400 (c) 200
  6. 6.Best estimate of 519 + 514? (a) 1000 (b) 800 (c) 1200
  7. 7.Best estimate of 159 + 676? (a) 900 (b) 700 (c) 1100
  8. 8.Best estimate of 630 + 642? (a) 1000 (b) 1400 (c) 1200
  9. 9.Best estimate of 74 × 26? (a) 21000 (b) 2100 (c) 210
  10. 10.Best estimate of 381 + 172? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 76 × 31? (a) 24000 (b) 2400 (c) 240
  12. 12.Best estimate of 89 × 78? (a) 72000 (b) 7200 (c) 720
  13. 13.Best estimate of 386 + 222? (a) 400 (b) 800 (c) 600
  14. 14.Best estimate of 67 × 17? (a) 1400 (b) 140 (c) 14000
  15. 15.Best estimate of 46 × 73? (a) 3500 (b) 35000 (c) 350
  16. 16.Best estimate of 73 × 56? (a) 42000 (b) 420 (c) 4200
  17. 17.Best estimate of 229 + 667? (a) 1100 (b) 700 (c) 900
  18. 18.Best estimate of 29 × 86? (a) 270 (b) 27000 (c) 2700
  19. 19.Best estimate of 93 × 32? (a) 27000 (b) 270 (c) 2700
  20. 20.Best estimate of 486 + 562? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 263 + 635? (a) 900 (b) 700 (c) 1100
  22. 22.Best estimate of 16 × 30? (a) 600 (b) 6000 (c) 60
  23. 23.Best estimate of 641 + 732? (a) 1300 (b) 1500 (c) 1100
  24. 24.Best estimate of 168 + 515? (a) 500 (b) 900 (c) 700
  25. 25.Best estimate of 457 + 573? (a) 1300 (b) 900 (c) 1100
  26. 26.Best estimate of 294 + 151? (a) 500 (b) 300 (c) 700
  27. 27.Best estimate of 27 × 67? (a) 21000 (b) 210 (c) 2100
  28. 28.Best estimate of 43 × 90? (a) 3600 (b) 36000 (c) 360
  29. 29.Best estimate of 41 × 47? (a) 2000 (b) 200 (c) 20000
  30. 30.Best estimate of 312 + 352? (a) 700 (b) 500 (c) 900
  31. 31.Best estimate of 42 × 67? (a) 2800 (b) 28000 (c) 280
  32. 32.Best estimate of 71 × 17? (a) 14000 (b) 1400 (c) 140
  33. 33.Best estimate of 30 × 74? (a) 2100 (b) 210 (c) 21000
  34. 34.Best estimate of 419 + 470? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 753 + 663? (a) 1700 (b) 1300 (c) 1500
  36. 36.Best estimate of 636 + 170? (a) 600 (b) 800 (c) 1000
  37. 37.Best estimate of 814 + 230? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 288 + 757? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 79 × 34? (a) 24000 (b) 2400 (c) 240
  40. 40.Best estimate of 39 × 17? (a) 80 (b) 800 (c) 8000

Answer key

  1. 2500
  2. 7000
  3. 1000
  4. 900
  5. 400
  6. 1000
  7. 900
  8. 1200
  9. 2100
  10. 600
  11. 2400
  12. 7200
  13. 600
  14. 1400
  15. 3500
  16. 4200
  17. 900
  18. 2700
  19. 2700
  20. 1100
  21. 900
  22. 600
  23. 1300
  24. 700
  25. 1100
  26. 500
  27. 2100
  28. 3600
  29. 2000
  30. 700
  31. 2800
  32. 1400
  33. 2100
  34. 900
  35. 1500
  36. 800
  37. 1000
  38. 1100
  39. 2400
  40. 800

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