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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 316 · 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 19 × 34? (a) 600 (b) 6000 (c) 60
  2. 2.Best estimate of 40 × 21? (a) 800 (b) 8000 (c) 80
  3. 3.Best estimate of 60 × 68? (a) 4200 (b) 42000 (c) 420
  4. 4.Best estimate of 56 × 59? (a) 360 (b) 36000 (c) 3600
  5. 5.Best estimate of 851 + 443? (a) 1100 (b) 1300 (c) 1500
  6. 6.Best estimate of 282 + 743? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 191 + 307? (a) 300 (b) 700 (c) 500
  8. 8.Best estimate of 36 × 41? (a) 1600 (b) 160 (c) 16000
  9. 9.Best estimate of 66 × 22? (a) 14000 (b) 140 (c) 1400
  10. 10.Best estimate of 19 × 96? (a) 2000 (b) 20000 (c) 200
  11. 11.Best estimate of 53 × 66? (a) 3500 (b) 350 (c) 35000
  12. 12.Best estimate of 302 + 322? (a) 800 (b) 600 (c) 400
  13. 13.Best estimate of 66 × 39? (a) 28000 (b) 2800 (c) 280
  14. 14.Best estimate of 570 + 530? (a) 900 (b) 1100 (c) 1300
  15. 15.Best estimate of 722 + 279? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 16 × 87? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 32 × 24? (a) 60 (b) 600 (c) 6000
  18. 18.Best estimate of 28 × 27? (a) 900 (b) 9000 (c) 90
  19. 19.Best estimate of 94 × 94? (a) 8100 (b) 810 (c) 81000
  20. 20.Best estimate of 87 × 48? (a) 4500 (b) 450 (c) 45000
  21. 21.Best estimate of 795 + 351? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 51 × 44? (a) 2000 (b) 20000 (c) 200
  23. 23.Best estimate of 392 + 373? (a) 600 (b) 800 (c) 1000
  24. 24.Best estimate of 373 + 568? (a) 1200 (b) 800 (c) 1000
  25. 25.Best estimate of 757 + 609? (a) 1600 (b) 1200 (c) 1400
  26. 26.Best estimate of 630 + 751? (a) 1400 (b) 1200 (c) 1600
  27. 27.Best estimate of 143 + 151? (a) 500 (b) 100 (c) 300
  28. 28.Best estimate of 662 + 352? (a) 900 (b) 1300 (c) 1100
  29. 29.Best estimate of 91 × 16? (a) 1800 (b) 18000 (c) 180
  30. 30.Best estimate of 70 × 73? (a) 490 (b) 49000 (c) 4900
  31. 31.Best estimate of 24 × 79? (a) 16000 (b) 160 (c) 1600
  32. 32.Best estimate of 206 + 631? (a) 1000 (b) 600 (c) 800
  33. 33.Best estimate of 210 + 859? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 58 × 26? (a) 180 (b) 1800 (c) 18000
  35. 35.Best estimate of 97 × 43? (a) 400 (b) 40000 (c) 4000
  36. 36.Best estimate of 776 + 875? (a) 1500 (b) 1900 (c) 1700
  37. 37.Best estimate of 23 × 20? (a) 40 (b) 400 (c) 4000
  38. 38.Best estimate of 381 + 647? (a) 800 (b) 1000 (c) 1200
  39. 39.Best estimate of 62 × 36? (a) 24000 (b) 2400 (c) 240
  40. 40.Best estimate of 332 + 679? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 600
  2. 800
  3. 4200
  4. 3600
  5. 1300
  6. 1000
  7. 500
  8. 1600
  9. 1400
  10. 2000
  11. 3500
  12. 600
  13. 2800
  14. 1100
  15. 1000
  16. 1800
  17. 600
  18. 900
  19. 8100
  20. 4500
  21. 1200
  22. 2000
  23. 800
  24. 1000
  25. 1400
  26. 1400
  27. 300
  28. 1100
  29. 1800
  30. 4900
  31. 1600
  32. 800
  33. 1100
  34. 1800
  35. 4000
  36. 1700
  37. 400
  38. 1000
  39. 2400
  40. 1000

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