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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 299 · 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 16 × 79? (a) 160 (b) 1600 (c) 16000
  2. 2.Best estimate of 50 × 13? (a) 5000 (b) 50 (c) 500
  3. 3.Best estimate of 465 + 129? (a) 800 (b) 600 (c) 400
  4. 4.Best estimate of 61 × 47? (a) 3000 (b) 300 (c) 30000
  5. 5.Best estimate of 70 × 96? (a) 70000 (b) 7000 (c) 700
  6. 6.Best estimate of 89 × 71? (a) 6300 (b) 630 (c) 63000
  7. 7.Best estimate of 634 + 610? (a) 1000 (b) 1400 (c) 1200
  8. 8.Best estimate of 60 × 79? (a) 480 (b) 48000 (c) 4800
  9. 9.Best estimate of 853 + 497? (a) 1600 (b) 1200 (c) 1400
  10. 10.Best estimate of 529 + 352? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 595 + 153? (a) 600 (b) 800 (c) 1000
  12. 12.Best estimate of 313 + 535? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 98 × 38? (a) 40000 (b) 4000 (c) 400
  14. 14.Best estimate of 49 × 48? (a) 2500 (b) 25000 (c) 250
  15. 15.Best estimate of 140 + 181? (a) 300 (b) 500 (c) 100
  16. 16.Best estimate of 451 + 251? (a) 800 (b) 1000 (c) 600
  17. 17.Best estimate of 46 × 34? (a) 1500 (b) 15000 (c) 150
  18. 18.Best estimate of 253 + 438? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 72 × 36? (a) 2800 (b) 280 (c) 28000
  20. 20.Best estimate of 573 + 179? (a) 600 (b) 1000 (c) 800
  21. 21.Best estimate of 78 × 87? (a) 72000 (b) 7200 (c) 720
  22. 22.Best estimate of 373 + 221? (a) 400 (b) 600 (c) 800
  23. 23.Best estimate of 154 + 377? (a) 600 (b) 800 (c) 400
  24. 24.Best estimate of 93 × 70? (a) 63000 (b) 6300 (c) 630
  25. 25.Best estimate of 16 × 38? (a) 8000 (b) 80 (c) 800
  26. 26.Best estimate of 98 × 23? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 16 × 68? (a) 140 (b) 1400 (c) 14000
  28. 28.Best estimate of 213 + 323? (a) 500 (b) 700 (c) 300
  29. 29.Best estimate of 34 × 96? (a) 300 (b) 30000 (c) 3000
  30. 30.Best estimate of 388 + 203? (a) 400 (b) 600 (c) 800
  31. 31.Best estimate of 33 × 43? (a) 12000 (b) 120 (c) 1200
  32. 32.Best estimate of 49 × 46? (a) 25000 (b) 2500 (c) 250
  33. 33.Best estimate of 63 × 26? (a) 1800 (b) 18000 (c) 180
  34. 34.Best estimate of 280 + 206? (a) 300 (b) 500 (c) 700
  35. 35.Best estimate of 69 × 32? (a) 2100 (b) 210 (c) 21000
  36. 36.Best estimate of 38 × 41? (a) 160 (b) 1600 (c) 16000
  37. 37.Best estimate of 76 × 24? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 72 × 58? (a) 42000 (b) 420 (c) 4200
  39. 39.Best estimate of 28 × 26? (a) 900 (b) 9000 (c) 90
  40. 40.Best estimate of 98 × 81? (a) 80000 (b) 800 (c) 8000

Answer key

  1. 1600
  2. 500
  3. 600
  4. 3000
  5. 7000
  6. 6300
  7. 1200
  8. 4800
  9. 1400
  10. 900
  11. 800
  12. 800
  13. 4000
  14. 2500
  15. 300
  16. 800
  17. 1500
  18. 700
  19. 2800
  20. 800
  21. 7200
  22. 600
  23. 600
  24. 6300
  25. 800
  26. 2000
  27. 1400
  28. 500
  29. 3000
  30. 600
  31. 1200
  32. 2500
  33. 1800
  34. 500
  35. 2100
  36. 1600
  37. 1600
  38. 4200
  39. 900
  40. 8000

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