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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 130 · 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 12 × 82? (a) 8000 (b) 80 (c) 800
  2. 2.Best estimate of 437 + 505? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 330 + 694? (a) 800 (b) 1200 (c) 1000
  4. 4.Best estimate of 69 × 27? (a) 21000 (b) 210 (c) 2100
  5. 5.Best estimate of 767 + 751? (a) 1600 (b) 1400 (c) 1800
  6. 6.Best estimate of 22 × 64? (a) 1200 (b) 12000 (c) 120
  7. 7.Best estimate of 27 × 46? (a) 15000 (b) 150 (c) 1500
  8. 8.Best estimate of 378 + 508? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 32 × 12? (a) 300 (b) 3000 (c) 30
  10. 10.Best estimate of 89 × 34? (a) 2700 (b) 270 (c) 27000
  11. 11.Best estimate of 819 + 463? (a) 1300 (b) 1500 (c) 1100
  12. 12.Best estimate of 526 + 799? (a) 1100 (b) 1500 (c) 1300
  13. 13.Best estimate of 247 + 573? (a) 600 (b) 800 (c) 1000
  14. 14.Best estimate of 43 × 60? (a) 240 (b) 24000 (c) 2400
  15. 15.Best estimate of 633 + 264? (a) 700 (b) 1100 (c) 900
  16. 16.Best estimate of 874 + 136? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 564 + 523? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 63 × 40? (a) 2400 (b) 240 (c) 24000
  19. 19.Best estimate of 71 × 60? (a) 4200 (b) 42000 (c) 420
  20. 20.Best estimate of 763 + 639? (a) 1200 (b) 1600 (c) 1400
  21. 21.Best estimate of 26 × 93? (a) 2700 (b) 27000 (c) 270
  22. 22.Best estimate of 49 × 91? (a) 450 (b) 45000 (c) 4500
  23. 23.Best estimate of 33 × 26? (a) 900 (b) 9000 (c) 90
  24. 24.Best estimate of 78 × 96? (a) 800 (b) 8000 (c) 80000
  25. 25.Best estimate of 481 + 745? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 93 × 54? (a) 4500 (b) 450 (c) 45000
  27. 27.Best estimate of 90 × 80? (a) 7200 (b) 720 (c) 72000
  28. 28.Best estimate of 469 + 228? (a) 500 (b) 900 (c) 700
  29. 29.Best estimate of 674 + 858? (a) 1800 (b) 1600 (c) 1400
  30. 30.Best estimate of 86 × 91? (a) 8100 (b) 81000 (c) 810
  31. 31.Best estimate of 79 × 92? (a) 7200 (b) 72000 (c) 720
  32. 32.Best estimate of 21 × 92? (a) 180 (b) 18000 (c) 1800
  33. 33.Best estimate of 97 × 38? (a) 400 (b) 40000 (c) 4000
  34. 34.Best estimate of 14 × 73? (a) 700 (b) 7000 (c) 70
  35. 35.Best estimate of 32 × 43? (a) 1200 (b) 120 (c) 12000
  36. 36.Best estimate of 38 × 44? (a) 16000 (b) 1600 (c) 160
  37. 37.Best estimate of 641 + 186? (a) 800 (b) 1000 (c) 600
  38. 38.Best estimate of 30 × 26? (a) 9000 (b) 900 (c) 90
  39. 39.Best estimate of 622 + 511? (a) 1300 (b) 900 (c) 1100
  40. 40.Best estimate of 751 + 191? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 800
  2. 900
  3. 1000
  4. 2100
  5. 1600
  6. 1200
  7. 1500
  8. 900
  9. 300
  10. 2700
  11. 1300
  12. 1300
  13. 800
  14. 2400
  15. 900
  16. 1000
  17. 1100
  18. 2400
  19. 4200
  20. 1400
  21. 2700
  22. 4500
  23. 900
  24. 8000
  25. 1200
  26. 4500
  27. 7200
  28. 700
  29. 1600
  30. 8100
  31. 7200
  32. 1800
  33. 4000
  34. 700
  35. 1200
  36. 1600
  37. 800
  38. 900
  39. 1100
  40. 1000

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