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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 275 · 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 601 + 416? (a) 800 (b) 1000 (c) 1200
  2. 2.Best estimate of 224 + 384? (a) 800 (b) 600 (c) 400
  3. 3.Best estimate of 338 + 162? (a) 700 (b) 300 (c) 500
  4. 4.Best estimate of 63 × 74? (a) 4200 (b) 420 (c) 42000
  5. 5.Best estimate of 466 + 493? (a) 800 (b) 1000 (c) 1200
  6. 6.Best estimate of 61 × 59? (a) 3600 (b) 36000 (c) 360
  7. 7.Best estimate of 40 × 77? (a) 32000 (b) 3200 (c) 320
  8. 8.Best estimate of 40 × 60? (a) 24000 (b) 240 (c) 2400
  9. 9.Best estimate of 670 + 291? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 36 × 93? (a) 3600 (b) 36000 (c) 360
  11. 11.Best estimate of 151 + 172? (a) 400 (b) 600 (c) 200
  12. 12.Best estimate of 22 × 59? (a) 120 (b) 1200 (c) 12000
  13. 13.Best estimate of 133 + 219? (a) 500 (b) 300 (c) 100
  14. 14.Best estimate of 639 + 703? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 98 × 30? (a) 3000 (b) 30000 (c) 300
  16. 16.Best estimate of 50 × 90? (a) 45000 (b) 4500 (c) 450
  17. 17.Best estimate of 37 × 74? (a) 280 (b) 2800 (c) 28000
  18. 18.Best estimate of 16 × 19? (a) 40 (b) 4000 (c) 400
  19. 19.Best estimate of 24 × 46? (a) 100 (b) 1000 (c) 10000
  20. 20.Best estimate of 61 × 29? (a) 1800 (b) 18000 (c) 180
  21. 21.Best estimate of 318 + 841? (a) 900 (b) 1100 (c) 1300
  22. 22.Best estimate of 740 + 473? (a) 1000 (b) 1200 (c) 1400
  23. 23.Best estimate of 190 + 686? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 547 + 855? (a) 1600 (b) 1400 (c) 1200
  25. 25.Best estimate of 348 + 548? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 77 × 23? (a) 1600 (b) 16000 (c) 160
  27. 27.Best estimate of 177 + 688? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 676 + 468? (a) 1000 (b) 1400 (c) 1200
  29. 29.Best estimate of 727 + 502? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 340 + 237? (a) 700 (b) 300 (c) 500
  31. 31.Best estimate of 29 × 79? (a) 2400 (b) 240 (c) 24000
  32. 32.Best estimate of 202 + 215? (a) 400 (b) 600 (c) 200
  33. 33.Best estimate of 64 × 92? (a) 54000 (b) 540 (c) 5400
  34. 34.Best estimate of 72 × 94? (a) 63000 (b) 630 (c) 6300
  35. 35.Best estimate of 668 + 162? (a) 1100 (b) 900 (c) 700
  36. 36.Best estimate of 52 × 14? (a) 500 (b) 50 (c) 5000
  37. 37.Best estimate of 16 × 27? (a) 6000 (b) 60 (c) 600
  38. 38.Best estimate of 298 + 657? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 79 × 17? (a) 160 (b) 16000 (c) 1600
  40. 40.Best estimate of 56 × 30? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 1000
  2. 600
  3. 500
  4. 4200
  5. 1000
  6. 3600
  7. 3200
  8. 2400
  9. 1000
  10. 3600
  11. 400
  12. 1200
  13. 300
  14. 1300
  15. 3000
  16. 4500
  17. 2800
  18. 400
  19. 1000
  20. 1800
  21. 1100
  22. 1200
  23. 900
  24. 1400
  25. 800
  26. 1600
  27. 900
  28. 1200
  29. 1200
  30. 500
  31. 2400
  32. 400
  33. 5400
  34. 6300
  35. 900
  36. 500
  37. 600
  38. 1000
  39. 1600
  40. 1800

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