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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 634 · 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 776 + 122? (a) 900 (b) 1100 (c) 700
  2. 2.Best estimate of 753 + 334? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 316 + 817? (a) 1100 (b) 900 (c) 1300
  4. 4.Best estimate of 47 × 84? (a) 40000 (b) 4000 (c) 400
  5. 5.Best estimate of 36 × 61? (a) 240 (b) 2400 (c) 24000
  6. 6.Best estimate of 93 × 78? (a) 7200 (b) 720 (c) 72000
  7. 7.Best estimate of 34 × 61? (a) 180 (b) 1800 (c) 18000
  8. 8.Best estimate of 332 + 874? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 14 × 74? (a) 700 (b) 70 (c) 7000
  10. 10.Best estimate of 246 + 690? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 54 × 56? (a) 3000 (b) 300 (c) 30000
  12. 12.Best estimate of 44 × 89? (a) 360 (b) 3600 (c) 36000
  13. 13.Best estimate of 81 × 16? (a) 1600 (b) 160 (c) 16000
  14. 14.Best estimate of 96 × 62? (a) 600 (b) 6000 (c) 60000
  15. 15.Best estimate of 340 + 322? (a) 400 (b) 600 (c) 800
  16. 16.Best estimate of 86 × 98? (a) 90000 (b) 9000 (c) 900
  17. 17.Best estimate of 43 × 36? (a) 160 (b) 1600 (c) 16000
  18. 18.Best estimate of 36 × 56? (a) 240 (b) 2400 (c) 24000
  19. 19.Best estimate of 724 + 832? (a) 1500 (b) 1300 (c) 1700
  20. 20.Best estimate of 72 × 98? (a) 7000 (b) 70000 (c) 700
  21. 21.Best estimate of 32 × 72? (a) 2100 (b) 21000 (c) 210
  22. 22.Best estimate of 530 + 209? (a) 900 (b) 500 (c) 700
  23. 23.Best estimate of 668 + 346? (a) 1200 (b) 1000 (c) 800
  24. 24.Best estimate of 29 × 27? (a) 90 (b) 900 (c) 9000
  25. 25.Best estimate of 14 × 21? (a) 2000 (b) 200 (c) 20
  26. 26.Best estimate of 26 × 50? (a) 150 (b) 1500 (c) 15000
  27. 27.Best estimate of 806 + 486? (a) 1300 (b) 1500 (c) 1100
  28. 28.Best estimate of 17 × 59? (a) 1200 (b) 120 (c) 12000
  29. 29.Best estimate of 459 + 197? (a) 700 (b) 900 (c) 500
  30. 30.Best estimate of 52 × 51? (a) 25000 (b) 2500 (c) 250
  31. 31.Best estimate of 49 × 36? (a) 200 (b) 2000 (c) 20000
  32. 32.Best estimate of 336 + 251? (a) 600 (b) 400 (c) 800
  33. 33.Best estimate of 97 × 36? (a) 4000 (b) 400 (c) 40000
  34. 34.Best estimate of 69 × 66? (a) 49000 (b) 490 (c) 4900
  35. 35.Best estimate of 58 × 48? (a) 3000 (b) 30000 (c) 300
  36. 36.Best estimate of 30 × 70? (a) 2100 (b) 21000 (c) 210
  37. 37.Best estimate of 23 × 26? (a) 60 (b) 6000 (c) 600
  38. 38.Best estimate of 51 × 92? (a) 4500 (b) 45000 (c) 450
  39. 39.Best estimate of 40 × 96? (a) 4000 (b) 40000 (c) 400
  40. 40.Best estimate of 12 × 26? (a) 3000 (b) 300 (c) 30

Answer key

  1. 900
  2. 1100
  3. 1100
  4. 4000
  5. 2400
  6. 7200
  7. 1800
  8. 1200
  9. 700
  10. 900
  11. 3000
  12. 3600
  13. 1600
  14. 6000
  15. 600
  16. 9000
  17. 1600
  18. 2400
  19. 1500
  20. 7000
  21. 2100
  22. 700
  23. 1000
  24. 900
  25. 200
  26. 1500
  27. 1300
  28. 1200
  29. 700
  30. 2500
  31. 2000
  32. 600
  33. 4000
  34. 4900
  35. 3000
  36. 2100
  37. 600
  38. 4500
  39. 4000
  40. 300

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