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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 976 · 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 33 × 76? (a) 24000 (b) 240 (c) 2400
  2. 2.Best estimate of 33 × 42? (a) 1200 (b) 120 (c) 12000
  3. 3.Best estimate of 347 + 653? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 287 + 410? (a) 700 (b) 900 (c) 500
  5. 5.Best estimate of 589 + 433? (a) 1200 (b) 1000 (c) 800
  6. 6.Best estimate of 18 × 89? (a) 18000 (b) 1800 (c) 180
  7. 7.Best estimate of 92 × 33? (a) 270 (b) 2700 (c) 27000
  8. 8.Best estimate of 42 × 52? (a) 200 (b) 2000 (c) 20000
  9. 9.Best estimate of 856 + 312? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 613 + 812? (a) 1400 (b) 1200 (c) 1600
  11. 11.Best estimate of 682 + 503? (a) 1000 (b) 1400 (c) 1200
  12. 12.Best estimate of 78 × 71? (a) 5600 (b) 560 (c) 56000
  13. 13.Best estimate of 13 × 79? (a) 80 (b) 800 (c) 8000
  14. 14.Best estimate of 33 × 72? (a) 21000 (b) 2100 (c) 210
  15. 15.Best estimate of 52 × 17? (a) 1000 (b) 100 (c) 10000
  16. 16.Best estimate of 553 + 863? (a) 1300 (b) 1500 (c) 1700
  17. 17.Best estimate of 82 × 34? (a) 240 (b) 24000 (c) 2400
  18. 18.Best estimate of 153 + 216? (a) 600 (b) 200 (c) 400
  19. 19.Best estimate of 21 × 66? (a) 1400 (b) 14000 (c) 140
  20. 20.Best estimate of 155 + 817? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 612 + 544? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 446 + 151? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 364 + 419? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 13 × 52? (a) 50 (b) 500 (c) 5000
  25. 25.Best estimate of 588 + 185? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 771 + 617? (a) 1400 (b) 1600 (c) 1200
  27. 27.Best estimate of 448 + 729? (a) 900 (b) 1300 (c) 1100
  28. 28.Best estimate of 87 × 50? (a) 45000 (b) 4500 (c) 450
  29. 29.Best estimate of 851 + 267? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 323 + 668? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 18 × 41? (a) 8000 (b) 800 (c) 80
  32. 32.Best estimate of 347 + 522? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 34 × 30? (a) 90 (b) 9000 (c) 900
  34. 34.Best estimate of 363 + 465? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 188 + 296? (a) 500 (b) 300 (c) 700
  36. 36.Best estimate of 318 + 853? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 878 + 580? (a) 1700 (b) 1300 (c) 1500
  38. 38.Best estimate of 96 × 72? (a) 7000 (b) 700 (c) 70000
  39. 39.Best estimate of 31 × 91? (a) 270 (b) 2700 (c) 27000
  40. 40.Best estimate of 37 × 42? (a) 16000 (b) 1600 (c) 160

Answer key

  1. 2400
  2. 1200
  3. 1000
  4. 700
  5. 1000
  6. 1800
  7. 2700
  8. 2000
  9. 1200
  10. 1400
  11. 1200
  12. 5600
  13. 800
  14. 2100
  15. 1000
  16. 1500
  17. 2400
  18. 400
  19. 1400
  20. 1000
  21. 1100
  22. 600
  23. 800
  24. 500
  25. 800
  26. 1400
  27. 1100
  28. 4500
  29. 1200
  30. 1000
  31. 800
  32. 800
  33. 900
  34. 900
  35. 500
  36. 1200
  37. 1500
  38. 7000
  39. 2700
  40. 1600

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