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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 119 · 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 428 + 520? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 290 + 756? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 725 + 430? (a) 900 (b) 1300 (c) 1100
  4. 4.Best estimate of 61 × 18? (a) 12000 (b) 120 (c) 1200
  5. 5.Best estimate of 583 + 857? (a) 1500 (b) 1700 (c) 1300
  6. 6.Best estimate of 751 + 573? (a) 1600 (b) 1200 (c) 1400
  7. 7.Best estimate of 778 + 603? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 803 + 533? (a) 1500 (b) 1100 (c) 1300
  9. 9.Best estimate of 157 + 754? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 719 + 480? (a) 1000 (b) 1200 (c) 1400
  11. 11.Best estimate of 667 + 268? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 48 × 93? (a) 45000 (b) 4500 (c) 450
  13. 13.Best estimate of 432 + 652? (a) 1300 (b) 900 (c) 1100
  14. 14.Best estimate of 386 + 841? (a) 1200 (b) 1000 (c) 1400
  15. 15.Best estimate of 211 + 166? (a) 200 (b) 400 (c) 600
  16. 16.Best estimate of 66 × 88? (a) 6300 (b) 63000 (c) 630
  17. 17.Best estimate of 151 + 334? (a) 500 (b) 700 (c) 300
  18. 18.Best estimate of 433 + 642? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 12 × 59? (a) 60 (b) 6000 (c) 600
  20. 20.Best estimate of 81 × 43? (a) 320 (b) 3200 (c) 32000
  21. 21.Best estimate of 50 × 18? (a) 100 (b) 10000 (c) 1000
  22. 22.Best estimate of 404 + 362? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 22 × 74? (a) 1400 (b) 14000 (c) 140
  24. 24.Best estimate of 40 × 97? (a) 40000 (b) 4000 (c) 400
  25. 25.Best estimate of 668 + 354? (a) 1300 (b) 900 (c) 1100
  26. 26.Best estimate of 30 × 12? (a) 300 (b) 3000 (c) 30
  27. 27.Best estimate of 23 × 27? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 23 × 43? (a) 80 (b) 8000 (c) 800
  29. 29.Best estimate of 36 × 83? (a) 3200 (b) 32000 (c) 320
  30. 30.Best estimate of 22 × 69? (a) 140 (b) 1400 (c) 14000
  31. 31.Best estimate of 511 + 490? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 28 × 17? (a) 600 (b) 6000 (c) 60
  33. 33.Best estimate of 87 × 90? (a) 81000 (b) 8100 (c) 810
  34. 34.Best estimate of 404 + 278? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 92 × 44? (a) 3600 (b) 360 (c) 36000
  36. 36.Best estimate of 152 + 319? (a) 300 (b) 700 (c) 500
  37. 37.Best estimate of 501 + 255? (a) 1000 (b) 600 (c) 800
  38. 38.Best estimate of 69 × 34? (a) 21000 (b) 210 (c) 2100
  39. 39.Best estimate of 27 × 13? (a) 300 (b) 30 (c) 3000
  40. 40.Best estimate of 46 × 16? (a) 1000 (b) 10000 (c) 100

Answer key

  1. 900
  2. 1100
  3. 1100
  4. 1200
  5. 1500
  6. 1400
  7. 1400
  8. 1300
  9. 1000
  10. 1200
  11. 1000
  12. 4500
  13. 1100
  14. 1200
  15. 400
  16. 6300
  17. 500
  18. 1000
  19. 600
  20. 3200
  21. 1000
  22. 800
  23. 1400
  24. 4000
  25. 1100
  26. 300
  27. 600
  28. 800
  29. 3200
  30. 1400
  31. 1000
  32. 600
  33. 8100
  34. 700
  35. 3600
  36. 500
  37. 800
  38. 2100
  39. 300
  40. 1000

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