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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 125 · 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 41 × 53? (a) 200 (b) 20000 (c) 2000
  2. 2.Best estimate of 83 × 36? (a) 3200 (b) 32000 (c) 320
  3. 3.Best estimate of 14 × 50? (a) 50 (b) 500 (c) 5000
  4. 4.Best estimate of 869 + 441? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 16 × 12? (a) 2000 (b) 200 (c) 20
  6. 6.Best estimate of 20 × 16? (a) 4000 (b) 40 (c) 400
  7. 7.Best estimate of 54 × 48? (a) 25000 (b) 2500 (c) 250
  8. 8.Best estimate of 769 + 143? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 52 × 19? (a) 100 (b) 10000 (c) 1000
  10. 10.Best estimate of 854 + 622? (a) 1500 (b) 1700 (c) 1300
  11. 11.Best estimate of 49 × 28? (a) 1500 (b) 15000 (c) 150
  12. 12.Best estimate of 23 × 86? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 800 + 462? (a) 1500 (b) 1300 (c) 1100
  14. 14.Best estimate of 47 × 50? (a) 250 (b) 2500 (c) 25000
  15. 15.Best estimate of 88 × 80? (a) 7200 (b) 72000 (c) 720
  16. 16.Best estimate of 60 × 16? (a) 12000 (b) 120 (c) 1200
  17. 17.Best estimate of 40 × 43? (a) 16000 (b) 160 (c) 1600
  18. 18.Best estimate of 263 + 315? (a) 600 (b) 400 (c) 800
  19. 19.Best estimate of 94 × 72? (a) 630 (b) 63000 (c) 6300
  20. 20.Best estimate of 518 + 255? (a) 600 (b) 1000 (c) 800
  21. 21.Best estimate of 495 + 431? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 819 + 545? (a) 1500 (b) 1100 (c) 1300
  23. 23.Best estimate of 490 + 235? (a) 700 (b) 900 (c) 500
  24. 24.Best estimate of 33 × 33? (a) 900 (b) 90 (c) 9000
  25. 25.Best estimate of 77 × 83? (a) 640 (b) 64000 (c) 6400
  26. 26.Best estimate of 476 + 555? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 758 + 780? (a) 1800 (b) 1600 (c) 1400
  28. 28.Best estimate of 89 × 56? (a) 5400 (b) 54000 (c) 540
  29. 29.Best estimate of 62 × 19? (a) 12000 (b) 1200 (c) 120
  30. 30.Best estimate of 27 × 23? (a) 60 (b) 6000 (c) 600
  31. 31.Best estimate of 41 × 57? (a) 240 (b) 2400 (c) 24000
  32. 32.Best estimate of 620 + 774? (a) 1600 (b) 1400 (c) 1200
  33. 33.Best estimate of 531 + 236? (a) 700 (b) 500 (c) 900
  34. 34.Best estimate of 659 + 215? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 652 + 815? (a) 1500 (b) 1700 (c) 1300
  36. 36.Best estimate of 33 × 56? (a) 18000 (b) 180 (c) 1800
  37. 37.Best estimate of 88 × 40? (a) 36000 (b) 3600 (c) 360
  38. 38.Best estimate of 16 × 58? (a) 1200 (b) 12000 (c) 120
  39. 39.Best estimate of 87 × 57? (a) 54000 (b) 5400 (c) 540
  40. 40.Best estimate of 167 + 548? (a) 700 (b) 500 (c) 900

Answer key

  1. 2000
  2. 3200
  3. 500
  4. 1300
  5. 200
  6. 400
  7. 2500
  8. 900
  9. 1000
  10. 1500
  11. 1500
  12. 1800
  13. 1300
  14. 2500
  15. 7200
  16. 1200
  17. 1600
  18. 600
  19. 6300
  20. 800
  21. 900
  22. 1300
  23. 700
  24. 900
  25. 6400
  26. 1100
  27. 1600
  28. 5400
  29. 1200
  30. 600
  31. 2400
  32. 1400
  33. 700
  34. 900
  35. 1500
  36. 1800
  37. 3600
  38. 1200
  39. 5400
  40. 700

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