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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 987 · 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 26 × 87? (a) 270 (b) 27000 (c) 2700
  2. 2.Best estimate of 174 + 222? (a) 200 (b) 400 (c) 600
  3. 3.Best estimate of 61 × 61? (a) 3600 (b) 360 (c) 36000
  4. 4.Best estimate of 689 + 769? (a) 1500 (b) 1700 (c) 1300
  5. 5.Best estimate of 16 × 64? (a) 1200 (b) 12000 (c) 120
  6. 6.Best estimate of 22 × 91? (a) 18000 (b) 180 (c) 1800
  7. 7.Best estimate of 244 + 433? (a) 400 (b) 600 (c) 800
  8. 8.Best estimate of 442 + 163? (a) 400 (b) 600 (c) 800
  9. 9.Best estimate of 34 × 16? (a) 600 (b) 60 (c) 6000
  10. 10.Best estimate of 478 + 237? (a) 900 (b) 500 (c) 700
  11. 11.Best estimate of 248 + 872? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 61 × 81? (a) 4800 (b) 48000 (c) 480
  13. 13.Best estimate of 13 × 36? (a) 4000 (b) 40 (c) 400
  14. 14.Best estimate of 29 × 74? (a) 21000 (b) 210 (c) 2100
  15. 15.Best estimate of 278 + 320? (a) 600 (b) 800 (c) 400
  16. 16.Best estimate of 33 × 79? (a) 240 (b) 2400 (c) 24000
  17. 17.Best estimate of 380 + 693? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 633 + 137? (a) 700 (b) 500 (c) 900
  19. 19.Best estimate of 185 + 801? (a) 800 (b) 1000 (c) 1200
  20. 20.Best estimate of 217 + 229? (a) 400 (b) 200 (c) 600
  21. 21.Best estimate of 445 + 141? (a) 300 (b) 700 (c) 500
  22. 22.Best estimate of 97 × 76? (a) 800 (b) 8000 (c) 80000
  23. 23.Best estimate of 716 + 398? (a) 1100 (b) 900 (c) 1300
  24. 24.Best estimate of 69 × 50? (a) 3500 (b) 35000 (c) 350
  25. 25.Best estimate of 67 × 78? (a) 56000 (b) 5600 (c) 560
  26. 26.Best estimate of 93 × 81? (a) 7200 (b) 720 (c) 72000
  27. 27.Best estimate of 34 × 97? (a) 3000 (b) 30000 (c) 300
  28. 28.Best estimate of 96 × 37? (a) 40000 (b) 400 (c) 4000
  29. 29.Best estimate of 52 × 46? (a) 2500 (b) 250 (c) 25000
  30. 30.Best estimate of 171 + 389? (a) 600 (b) 800 (c) 400
  31. 31.Best estimate of 772 + 587? (a) 1200 (b) 1600 (c) 1400
  32. 32.Best estimate of 44 × 94? (a) 360 (b) 36000 (c) 3600
  33. 33.Best estimate of 755 + 266? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 263 + 171? (a) 700 (b) 500 (c) 300
  35. 35.Best estimate of 399 + 861? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 30 × 50? (a) 15000 (b) 150 (c) 1500
  37. 37.Best estimate of 47 × 83? (a) 4000 (b) 400 (c) 40000
  38. 38.Best estimate of 330 + 619? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 86 × 67? (a) 6300 (b) 63000 (c) 630
  40. 40.Best estimate of 50 × 90? (a) 450 (b) 45000 (c) 4500

Answer key

  1. 2700
  2. 400
  3. 3600
  4. 1500
  5. 1200
  6. 1800
  7. 600
  8. 600
  9. 600
  10. 700
  11. 1100
  12. 4800
  13. 400
  14. 2100
  15. 600
  16. 2400
  17. 1100
  18. 700
  19. 1000
  20. 400
  21. 500
  22. 8000
  23. 1100
  24. 3500
  25. 5600
  26. 7200
  27. 3000
  28. 4000
  29. 2500
  30. 600
  31. 1400
  32. 3600
  33. 1100
  34. 500
  35. 1300
  36. 1500
  37. 4000
  38. 900
  39. 6300
  40. 4500

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