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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 902 · 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 67 × 52? (a) 35000 (b) 350 (c) 3500
  2. 2.Best estimate of 771 + 347? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 209 + 226? (a) 400 (b) 600 (c) 200
  4. 4.Best estimate of 86 × 14? (a) 90 (b) 9000 (c) 900
  5. 5.Best estimate of 586 + 141? (a) 700 (b) 500 (c) 900
  6. 6.Best estimate of 160 + 677? (a) 900 (b) 700 (c) 1100
  7. 7.Best estimate of 280 + 620? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 39 × 76? (a) 3200 (b) 32000 (c) 320
  9. 9.Best estimate of 62 × 90? (a) 5400 (b) 54000 (c) 540
  10. 10.Best estimate of 73 × 34? (a) 210 (b) 21000 (c) 2100
  11. 11.Best estimate of 652 + 405? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 437 + 157? (a) 600 (b) 400 (c) 800
  13. 13.Best estimate of 57 × 19? (a) 120 (b) 1200 (c) 12000
  14. 14.Best estimate of 86 × 93? (a) 81000 (b) 8100 (c) 810
  15. 15.Best estimate of 382 + 136? (a) 300 (b) 500 (c) 700
  16. 16.Best estimate of 69 × 87? (a) 6300 (b) 63000 (c) 630
  17. 17.Best estimate of 733 + 237? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 174 + 196? (a) 400 (b) 600 (c) 200
  19. 19.Best estimate of 56 × 89? (a) 54000 (b) 5400 (c) 540
  20. 20.Best estimate of 71 × 26? (a) 210 (b) 21000 (c) 2100
  21. 21.Best estimate of 862 + 652? (a) 1600 (b) 1800 (c) 1400
  22. 22.Best estimate of 583 + 304? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 36 × 27? (a) 12000 (b) 1200 (c) 120
  24. 24.Best estimate of 91 × 39? (a) 360 (b) 3600 (c) 36000
  25. 25.Best estimate of 700 + 190? (a) 1100 (b) 700 (c) 900
  26. 26.Best estimate of 36 × 93? (a) 360 (b) 3600 (c) 36000
  27. 27.Best estimate of 31 × 64? (a) 180 (b) 1800 (c) 18000
  28. 28.Best estimate of 36 × 66? (a) 2800 (b) 28000 (c) 280
  29. 29.Best estimate of 49 × 66? (a) 35000 (b) 350 (c) 3500
  30. 30.Best estimate of 628 + 369? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 139 + 476? (a) 600 (b) 800 (c) 400
  32. 32.Best estimate of 30 × 32? (a) 90 (b) 900 (c) 9000
  33. 33.Best estimate of 74 × 91? (a) 630 (b) 6300 (c) 63000
  34. 34.Best estimate of 494 + 721? (a) 1000 (b) 1200 (c) 1400
  35. 35.Best estimate of 50 × 80? (a) 40000 (b) 400 (c) 4000
  36. 36.Best estimate of 30 × 53? (a) 150 (b) 1500 (c) 15000
  37. 37.Best estimate of 17 × 56? (a) 12000 (b) 120 (c) 1200
  38. 38.Best estimate of 81 × 98? (a) 8000 (b) 800 (c) 80000
  39. 39.Best estimate of 88 × 40? (a) 36000 (b) 360 (c) 3600
  40. 40.Best estimate of 97 × 40? (a) 4000 (b) 40000 (c) 400

Answer key

  1. 3500
  2. 1100
  3. 400
  4. 900
  5. 700
  6. 900
  7. 900
  8. 3200
  9. 5400
  10. 2100
  11. 1100
  12. 600
  13. 1200
  14. 8100
  15. 500
  16. 6300
  17. 900
  18. 400
  19. 5400
  20. 2100
  21. 1600
  22. 900
  23. 1200
  24. 3600
  25. 900
  26. 3600
  27. 1800
  28. 2800
  29. 3500
  30. 1000
  31. 600
  32. 900
  33. 6300
  34. 1200
  35. 4000
  36. 1500
  37. 1200
  38. 8000
  39. 3600
  40. 4000

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