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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 512 · 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 34 × 79? (a) 24000 (b) 240 (c) 2400
  2. 2.Best estimate of 203 + 459? (a) 700 (b) 500 (c) 900
  3. 3.Best estimate of 778 + 670? (a) 1700 (b) 1500 (c) 1300
  4. 4.Best estimate of 61 × 98? (a) 600 (b) 6000 (c) 60000
  5. 5.Best estimate of 98 × 46? (a) 500 (b) 50000 (c) 5000
  6. 6.Best estimate of 50 × 74? (a) 350 (b) 3500 (c) 35000
  7. 7.Best estimate of 66 × 79? (a) 56000 (b) 560 (c) 5600
  8. 8.Best estimate of 46 × 73? (a) 3500 (b) 35000 (c) 350
  9. 9.Best estimate of 58 × 76? (a) 4800 (b) 480 (c) 48000
  10. 10.Best estimate of 76 × 97? (a) 80000 (b) 8000 (c) 800
  11. 11.Best estimate of 83 × 69? (a) 56000 (b) 5600 (c) 560
  12. 12.Best estimate of 43 × 91? (a) 3600 (b) 36000 (c) 360
  13. 13.Best estimate of 622 + 604? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 731 + 406? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 704 + 227? (a) 1100 (b) 700 (c) 900
  16. 16.Best estimate of 487 + 655? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 275 + 294? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 154 + 482? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 23 × 56? (a) 120 (b) 12000 (c) 1200
  20. 20.Best estimate of 41 × 94? (a) 3600 (b) 360 (c) 36000
  21. 21.Best estimate of 793 + 668? (a) 1500 (b) 1300 (c) 1700
  22. 22.Best estimate of 170 + 843? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 72 × 76? (a) 56000 (b) 560 (c) 5600
  24. 24.Best estimate of 56 × 52? (a) 3000 (b) 300 (c) 30000
  25. 25.Best estimate of 49 × 28? (a) 1500 (b) 150 (c) 15000
  26. 26.Best estimate of 206 + 179? (a) 600 (b) 400 (c) 200
  27. 27.Best estimate of 13 × 83? (a) 80 (b) 8000 (c) 800
  28. 28.Best estimate of 611 + 340? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 46 × 97? (a) 5000 (b) 500 (c) 50000
  30. 30.Best estimate of 632 + 417? (a) 1000 (b) 800 (c) 1200
  31. 31.Best estimate of 24 × 63? (a) 12000 (b) 1200 (c) 120
  32. 32.Best estimate of 93 × 93? (a) 8100 (b) 81000 (c) 810
  33. 33.Best estimate of 80 × 39? (a) 3200 (b) 320 (c) 32000
  34. 34.Best estimate of 292 + 279? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 335 + 323? (a) 600 (b) 800 (c) 400
  36. 36.Best estimate of 677 + 351? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 598 + 515? (a) 1300 (b) 900 (c) 1100
  38. 38.Best estimate of 23 × 42? (a) 8000 (b) 800 (c) 80
  39. 39.Best estimate of 66 × 56? (a) 42000 (b) 4200 (c) 420
  40. 40.Best estimate of 489 + 828? (a) 1500 (b) 1100 (c) 1300

Answer key

  1. 2400
  2. 700
  3. 1500
  4. 6000
  5. 5000
  6. 3500
  7. 5600
  8. 3500
  9. 4800
  10. 8000
  11. 5600
  12. 3600
  13. 1200
  14. 1100
  15. 900
  16. 1200
  17. 600
  18. 700
  19. 1200
  20. 3600
  21. 1500
  22. 1000
  23. 5600
  24. 3000
  25. 1500
  26. 400
  27. 800
  28. 900
  29. 5000
  30. 1000
  31. 1200
  32. 8100
  33. 3200
  34. 600
  35. 600
  36. 1100
  37. 1100
  38. 800
  39. 4200
  40. 1300

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