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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 399 · 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 859 + 500? (a) 1200 (b) 1600 (c) 1400
  2. 2.Best estimate of 51 × 19? (a) 100 (b) 10000 (c) 1000
  3. 3.Best estimate of 73 × 74? (a) 4900 (b) 49000 (c) 490
  4. 4.Best estimate of 87 × 56? (a) 5400 (b) 54000 (c) 540
  5. 5.Best estimate of 509 + 591? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 93 × 26? (a) 270 (b) 2700 (c) 27000
  7. 7.Best estimate of 477 + 592? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 61 × 92? (a) 54000 (b) 540 (c) 5400
  9. 9.Best estimate of 444 + 342? (a) 500 (b) 900 (c) 700
  10. 10.Best estimate of 613 + 402? (a) 800 (b) 1200 (c) 1000
  11. 11.Best estimate of 782 + 400? (a) 1200 (b) 1400 (c) 1000
  12. 12.Best estimate of 20 × 34? (a) 600 (b) 6000 (c) 60
  13. 13.Best estimate of 616 + 737? (a) 1100 (b) 1500 (c) 1300
  14. 14.Best estimate of 88 × 64? (a) 540 (b) 5400 (c) 54000
  15. 15.Best estimate of 374 + 459? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 32 × 31? (a) 9000 (b) 90 (c) 900
  17. 17.Best estimate of 26 × 92? (a) 2700 (b) 27000 (c) 270
  18. 18.Best estimate of 164 + 868? (a) 900 (b) 1300 (c) 1100
  19. 19.Best estimate of 362 + 480? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 49 × 23? (a) 100 (b) 1000 (c) 10000
  21. 21.Best estimate of 826 + 457? (a) 1300 (b) 1500 (c) 1100
  22. 22.Best estimate of 142 + 658? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 16 × 28? (a) 60 (b) 6000 (c) 600
  24. 24.Best estimate of 709 + 661? (a) 1400 (b) 1600 (c) 1200
  25. 25.Best estimate of 67 × 71? (a) 49000 (b) 4900 (c) 490
  26. 26.Best estimate of 58 × 22? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 70 × 50? (a) 3500 (b) 350 (c) 35000
  28. 28.Best estimate of 365 + 443? (a) 600 (b) 1000 (c) 800
  29. 29.Best estimate of 16 × 14? (a) 20 (b) 2000 (c) 200
  30. 30.Best estimate of 61 × 26? (a) 180 (b) 1800 (c) 18000
  31. 31.Best estimate of 88 × 31? (a) 27000 (b) 270 (c) 2700
  32. 32.Best estimate of 28 × 26? (a) 9000 (b) 90 (c) 900
  33. 33.Best estimate of 229 + 724? (a) 1100 (b) 700 (c) 900
  34. 34.Best estimate of 66 × 57? (a) 4200 (b) 420 (c) 42000
  35. 35.Best estimate of 54 × 71? (a) 35000 (b) 3500 (c) 350
  36. 36.Best estimate of 797 + 236? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 209 + 244? (a) 600 (b) 200 (c) 400
  38. 38.Best estimate of 43 × 96? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 37 × 83? (a) 32000 (b) 3200 (c) 320
  40. 40.Best estimate of 24 × 17? (a) 40 (b) 400 (c) 4000

Answer key

  1. 1400
  2. 1000
  3. 4900
  4. 5400
  5. 1100
  6. 2700
  7. 1100
  8. 5400
  9. 700
  10. 1000
  11. 1200
  12. 600
  13. 1300
  14. 5400
  15. 900
  16. 900
  17. 2700
  18. 1100
  19. 900
  20. 1000
  21. 1300
  22. 800
  23. 600
  24. 1400
  25. 4900
  26. 1200
  27. 3500
  28. 800
  29. 200
  30. 1800
  31. 2700
  32. 900
  33. 900
  34. 4200
  35. 3500
  36. 1000
  37. 400
  38. 4000
  39. 3200
  40. 400

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