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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 369 · 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 38 × 17? (a) 800 (b) 8000 (c) 80
  2. 2.Best estimate of 274 + 184? (a) 500 (b) 300 (c) 700
  3. 3.Best estimate of 567 + 140? (a) 700 (b) 500 (c) 900
  4. 4.Best estimate of 68 × 56? (a) 42000 (b) 4200 (c) 420
  5. 5.Best estimate of 720 + 422? (a) 1100 (b) 900 (c) 1300
  6. 6.Best estimate of 282 + 762? (a) 1100 (b) 1300 (c) 900
  7. 7.Best estimate of 32 × 87? (a) 2700 (b) 270 (c) 27000
  8. 8.Best estimate of 76 × 96? (a) 8000 (b) 80000 (c) 800
  9. 9.Best estimate of 189 + 506? (a) 500 (b) 900 (c) 700
  10. 10.Best estimate of 68 × 26? (a) 2100 (b) 210 (c) 21000
  11. 11.Best estimate of 22 × 16? (a) 4000 (b) 40 (c) 400
  12. 12.Best estimate of 249 + 818? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 32 × 92? (a) 2700 (b) 27000 (c) 270
  14. 14.Best estimate of 506 + 352? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 29 × 63? (a) 1800 (b) 180 (c) 18000
  16. 16.Best estimate of 16 × 57? (a) 1200 (b) 12000 (c) 120
  17. 17.Best estimate of 506 + 669? (a) 1400 (b) 1000 (c) 1200
  18. 18.Best estimate of 243 + 299? (a) 500 (b) 700 (c) 300
  19. 19.Best estimate of 58 × 74? (a) 42000 (b) 420 (c) 4200
  20. 20.Best estimate of 73 × 88? (a) 630 (b) 63000 (c) 6300
  21. 21.Best estimate of 789 + 263? (a) 900 (b) 1100 (c) 1300
  22. 22.Best estimate of 305 + 470? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 48 × 63? (a) 3000 (b) 300 (c) 30000
  24. 24.Best estimate of 240 + 736? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 87 × 80? (a) 7200 (b) 72000 (c) 720
  26. 26.Best estimate of 206 + 697? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 145 + 296? (a) 200 (b) 400 (c) 600
  28. 28.Best estimate of 88 × 17? (a) 180 (b) 18000 (c) 1800
  29. 29.Best estimate of 71 × 63? (a) 42000 (b) 4200 (c) 420
  30. 30.Best estimate of 53 × 18? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 838 + 279? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 90 × 64? (a) 540 (b) 5400 (c) 54000
  33. 33.Best estimate of 76 × 12? (a) 8000 (b) 800 (c) 80
  34. 34.Best estimate of 26 × 27? (a) 9000 (b) 900 (c) 90
  35. 35.Best estimate of 452 + 228? (a) 500 (b) 900 (c) 700
  36. 36.Best estimate of 46 × 92? (a) 4500 (b) 450 (c) 45000
  37. 37.Best estimate of 120 + 189? (a) 100 (b) 300 (c) 500
  38. 38.Best estimate of 44 × 26? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 411 + 543? (a) 900 (b) 1100 (c) 700
  40. 40.Best estimate of 26 × 56? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 800
  2. 500
  3. 700
  4. 4200
  5. 1100
  6. 1100
  7. 2700
  8. 8000
  9. 700
  10. 2100
  11. 400
  12. 1000
  13. 2700
  14. 900
  15. 1800
  16. 1200
  17. 1200
  18. 500
  19. 4200
  20. 6300
  21. 1100
  22. 800
  23. 3000
  24. 900
  25. 7200
  26. 900
  27. 400
  28. 1800
  29. 4200
  30. 1000
  31. 1100
  32. 5400
  33. 800
  34. 900
  35. 700
  36. 4500
  37. 300
  38. 1200
  39. 900
  40. 1800

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