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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 641 · 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 46 × 71? (a) 35000 (b) 3500 (c) 350
  2. 2.Best estimate of 76 × 90? (a) 72000 (b) 7200 (c) 720
  3. 3.Best estimate of 307 + 443? (a) 900 (b) 500 (c) 700
  4. 4.Best estimate of 66 × 76? (a) 560 (b) 56000 (c) 5600
  5. 5.Best estimate of 581 + 328? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 69 × 60? (a) 4200 (b) 420 (c) 42000
  7. 7.Best estimate of 238 + 291? (a) 300 (b) 700 (c) 500
  8. 8.Best estimate of 304 + 303? (a) 400 (b) 600 (c) 800
  9. 9.Best estimate of 570 + 624? (a) 1200 (b) 1400 (c) 1000
  10. 10.Best estimate of 413 + 584? (a) 1200 (b) 800 (c) 1000
  11. 11.Best estimate of 46 × 91? (a) 4500 (b) 450 (c) 45000
  12. 12.Best estimate of 31 × 70? (a) 21000 (b) 210 (c) 2100
  13. 13.Best estimate of 240 + 473? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 46 × 76? (a) 400 (b) 4000 (c) 40000
  15. 15.Best estimate of 36 × 53? (a) 20000 (b) 200 (c) 2000
  16. 16.Best estimate of 458 + 668? (a) 1400 (b) 1000 (c) 1200
  17. 17.Best estimate of 52 × 71? (a) 350 (b) 35000 (c) 3500
  18. 18.Best estimate of 38 × 76? (a) 320 (b) 3200 (c) 32000
  19. 19.Best estimate of 624 + 186? (a) 800 (b) 600 (c) 1000
  20. 20.Best estimate of 17 × 29? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 758 + 847? (a) 1400 (b) 1600 (c) 1800
  22. 22.Best estimate of 23 × 61? (a) 120 (b) 1200 (c) 12000
  23. 23.Best estimate of 68 × 16? (a) 14000 (b) 1400 (c) 140
  24. 24.Best estimate of 710 + 287? (a) 1200 (b) 800 (c) 1000
  25. 25.Best estimate of 47 × 42? (a) 200 (b) 2000 (c) 20000
  26. 26.Best estimate of 232 + 223? (a) 400 (b) 200 (c) 600
  27. 27.Best estimate of 70 × 66? (a) 490 (b) 4900 (c) 49000
  28. 28.Best estimate of 265 + 223? (a) 700 (b) 300 (c) 500
  29. 29.Best estimate of 26 × 41? (a) 12000 (b) 1200 (c) 120
  30. 30.Best estimate of 458 + 332? (a) 1000 (b) 600 (c) 800
  31. 31.Best estimate of 13 × 77? (a) 800 (b) 80 (c) 8000
  32. 32.Best estimate of 89 × 60? (a) 540 (b) 54000 (c) 5400
  33. 33.Best estimate of 12 × 12? (a) 100 (b) 10 (c) 1000
  34. 34.Best estimate of 763 + 120? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 31 × 71? (a) 21000 (b) 2100 (c) 210
  36. 36.Best estimate of 498 + 716? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 98 × 67? (a) 700 (b) 70000 (c) 7000
  38. 38.Best estimate of 13 × 78? (a) 800 (b) 8000 (c) 80
  39. 39.Best estimate of 89 × 26? (a) 27000 (b) 270 (c) 2700
  40. 40.Best estimate of 20 × 17? (a) 40 (b) 4000 (c) 400

Answer key

  1. 3500
  2. 7200
  3. 700
  4. 5600
  5. 900
  6. 4200
  7. 500
  8. 600
  9. 1200
  10. 1000
  11. 4500
  12. 2100
  13. 700
  14. 4000
  15. 2000
  16. 1200
  17. 3500
  18. 3200
  19. 800
  20. 600
  21. 1600
  22. 1200
  23. 1400
  24. 1000
  25. 2000
  26. 400
  27. 4900
  28. 500
  29. 1200
  30. 800
  31. 800
  32. 5400
  33. 100
  34. 900
  35. 2100
  36. 1200
  37. 7000
  38. 800
  39. 2700
  40. 400

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