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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 116 · 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 96 × 96? (a) 100000 (b) 1000 (c) 10000
  2. 2.Best estimate of 67 × 82? (a) 56000 (b) 560 (c) 5600
  3. 3.Best estimate of 325 + 236? (a) 700 (b) 500 (c) 300
  4. 4.Best estimate of 653 + 204? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 240 + 521? (a) 700 (b) 900 (c) 500
  6. 6.Best estimate of 32 × 33? (a) 9000 (b) 90 (c) 900
  7. 7.Best estimate of 54 × 20? (a) 10000 (b) 1000 (c) 100
  8. 8.Best estimate of 204 + 123? (a) 300 (b) 500 (c) 100
  9. 9.Best estimate of 418 + 608? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 76 × 38? (a) 320 (b) 32000 (c) 3200
  11. 11.Best estimate of 644 + 245? (a) 1000 (b) 600 (c) 800
  12. 12.Best estimate of 743 + 218? (a) 1100 (b) 900 (c) 700
  13. 13.Best estimate of 836 + 446? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 319 + 566? (a) 700 (b) 1100 (c) 900
  15. 15.Best estimate of 28 × 67? (a) 2100 (b) 21000 (c) 210
  16. 16.Best estimate of 287 + 553? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 12 × 32? (a) 300 (b) 3000 (c) 30
  18. 18.Best estimate of 224 + 228? (a) 200 (b) 400 (c) 600
  19. 19.Best estimate of 79 × 21? (a) 160 (b) 1600 (c) 16000
  20. 20.Best estimate of 16 × 39? (a) 800 (b) 8000 (c) 80
  21. 21.Best estimate of 412 + 452? (a) 1100 (b) 900 (c) 700
  22. 22.Best estimate of 69 × 21? (a) 1400 (b) 140 (c) 14000
  23. 23.Best estimate of 429 + 490? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 678 + 294? (a) 800 (b) 1000 (c) 1200
  25. 25.Best estimate of 86 × 16? (a) 18000 (b) 1800 (c) 180
  26. 26.Best estimate of 92 × 67? (a) 63000 (b) 6300 (c) 630
  27. 27.Best estimate of 438 + 267? (a) 900 (b) 500 (c) 700
  28. 28.Best estimate of 52 × 54? (a) 25000 (b) 2500 (c) 250
  29. 29.Best estimate of 77 × 22? (a) 16000 (b) 1600 (c) 160
  30. 30.Best estimate of 72 × 57? (a) 42000 (b) 4200 (c) 420
  31. 31.Best estimate of 36 × 66? (a) 280 (b) 2800 (c) 28000
  32. 32.Best estimate of 89 × 96? (a) 90000 (b) 9000 (c) 900
  33. 33.Best estimate of 541 + 410? (a) 900 (b) 700 (c) 1100
  34. 34.Best estimate of 82 × 38? (a) 3200 (b) 32000 (c) 320
  35. 35.Best estimate of 71 × 22? (a) 140 (b) 1400 (c) 14000
  36. 36.Best estimate of 18 × 81? (a) 160 (b) 1600 (c) 16000
  37. 37.Best estimate of 163 + 547? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 98 × 96? (a) 100000 (b) 10000 (c) 1000
  39. 39.Best estimate of 276 + 736? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 29 × 92? (a) 27000 (b) 2700 (c) 270

Answer key

  1. 10000
  2. 5600
  3. 500
  4. 900
  5. 700
  6. 900
  7. 1000
  8. 300
  9. 1000
  10. 3200
  11. 800
  12. 900
  13. 1200
  14. 900
  15. 2100
  16. 900
  17. 300
  18. 400
  19. 1600
  20. 800
  21. 900
  22. 1400
  23. 900
  24. 1000
  25. 1800
  26. 6300
  27. 700
  28. 2500
  29. 1600
  30. 4200
  31. 2800
  32. 9000
  33. 900
  34. 3200
  35. 1400
  36. 1600
  37. 700
  38. 10000
  39. 1000
  40. 2700

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