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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 758 · 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 81 × 57? (a) 480 (b) 48000 (c) 4800
  2. 2.Best estimate of 46 × 17? (a) 100 (b) 1000 (c) 10000
  3. 3.Best estimate of 16 × 19? (a) 4000 (b) 40 (c) 400
  4. 4.Best estimate of 40 × 51? (a) 2000 (b) 200 (c) 20000
  5. 5.Best estimate of 47 × 56? (a) 3000 (b) 300 (c) 30000
  6. 6.Best estimate of 813 + 237? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 59 × 26? (a) 18000 (b) 1800 (c) 180
  8. 8.Best estimate of 22 × 17? (a) 40 (b) 400 (c) 4000
  9. 9.Best estimate of 299 + 799? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 28 × 94? (a) 270 (b) 2700 (c) 27000
  11. 11.Best estimate of 67 × 17? (a) 140 (b) 1400 (c) 14000
  12. 12.Best estimate of 36 × 97? (a) 40000 (b) 400 (c) 4000
  13. 13.Best estimate of 51 × 31? (a) 150 (b) 1500 (c) 15000
  14. 14.Best estimate of 340 + 745? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 22 × 86? (a) 18000 (b) 180 (c) 1800
  16. 16.Best estimate of 32 × 77? (a) 2400 (b) 24000 (c) 240
  17. 17.Best estimate of 31 × 21? (a) 600 (b) 6000 (c) 60
  18. 18.Best estimate of 60 × 49? (a) 3000 (b) 300 (c) 30000
  19. 19.Best estimate of 436 + 257? (a) 700 (b) 500 (c) 900
  20. 20.Best estimate of 875 + 853? (a) 1600 (b) 1800 (c) 2000
  21. 21.Best estimate of 362 + 239? (a) 600 (b) 800 (c) 400
  22. 22.Best estimate of 127 + 309? (a) 400 (b) 200 (c) 600
  23. 23.Best estimate of 67 × 96? (a) 700 (b) 7000 (c) 70000
  24. 24.Best estimate of 862 + 189? (a) 900 (b) 1100 (c) 1300
  25. 25.Best estimate of 57 × 86? (a) 5400 (b) 540 (c) 54000
  26. 26.Best estimate of 78 × 56? (a) 48000 (b) 4800 (c) 480
  27. 27.Best estimate of 43 × 52? (a) 20000 (b) 2000 (c) 200
  28. 28.Best estimate of 54 × 56? (a) 3000 (b) 300 (c) 30000
  29. 29.Best estimate of 52 × 26? (a) 150 (b) 1500 (c) 15000
  30. 30.Best estimate of 86 × 14? (a) 900 (b) 9000 (c) 90
  31. 31.Best estimate of 18 × 36? (a) 800 (b) 80 (c) 8000
  32. 32.Best estimate of 737 + 369? (a) 1100 (b) 900 (c) 1300
  33. 33.Best estimate of 386 + 413? (a) 1000 (b) 600 (c) 800
  34. 34.Best estimate of 59 × 73? (a) 420 (b) 4200 (c) 42000
  35. 35.Best estimate of 61 × 48? (a) 3000 (b) 30000 (c) 300
  36. 36.Best estimate of 19 × 72? (a) 1400 (b) 14000 (c) 140
  37. 37.Best estimate of 48 × 27? (a) 1500 (b) 150 (c) 15000
  38. 38.Best estimate of 647 + 165? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 12 × 20? (a) 200 (b) 2000 (c) 20
  40. 40.Best estimate of 34 × 14? (a) 3000 (b) 30 (c) 300

Answer key

  1. 4800
  2. 1000
  3. 400
  4. 2000
  5. 3000
  6. 1000
  7. 1800
  8. 400
  9. 1100
  10. 2700
  11. 1400
  12. 4000
  13. 1500
  14. 1000
  15. 1800
  16. 2400
  17. 600
  18. 3000
  19. 700
  20. 1800
  21. 600
  22. 400
  23. 7000
  24. 1100
  25. 5400
  26. 4800
  27. 2000
  28. 3000
  29. 1500
  30. 900
  31. 800
  32. 1100
  33. 800
  34. 4200
  35. 3000
  36. 1400
  37. 1500
  38. 800
  39. 200
  40. 300

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