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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 566 · 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 565 + 152? (a) 800 (b) 1000 (c) 600
  2. 2.Best estimate of 361 + 228? (a) 400 (b) 600 (c) 800
  3. 3.Best estimate of 40 × 96? (a) 40000 (b) 4000 (c) 400
  4. 4.Best estimate of 537 + 535? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 496 + 462? (a) 1200 (b) 1000 (c) 800
  6. 6.Best estimate of 728 + 120? (a) 800 (b) 600 (c) 1000
  7. 7.Best estimate of 51 × 53? (a) 2500 (b) 250 (c) 25000
  8. 8.Best estimate of 333 + 121? (a) 200 (b) 400 (c) 600
  9. 9.Best estimate of 32 × 78? (a) 240 (b) 24000 (c) 2400
  10. 10.Best estimate of 53 × 91? (a) 45000 (b) 450 (c) 4500
  11. 11.Best estimate of 67 × 33? (a) 2100 (b) 210 (c) 21000
  12. 12.Best estimate of 62 × 69? (a) 4200 (b) 42000 (c) 420
  13. 13.Best estimate of 258 + 244? (a) 700 (b) 300 (c) 500
  14. 14.Best estimate of 92 × 32? (a) 270 (b) 2700 (c) 27000
  15. 15.Best estimate of 865 + 273? (a) 1000 (b) 1400 (c) 1200
  16. 16.Best estimate of 31 × 34? (a) 900 (b) 9000 (c) 90
  17. 17.Best estimate of 354 + 328? (a) 500 (b) 700 (c) 900
  18. 18.Best estimate of 536 + 552? (a) 1100 (b) 1300 (c) 900
  19. 19.Best estimate of 91 × 60? (a) 540 (b) 5400 (c) 54000
  20. 20.Best estimate of 23 × 33? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 74 × 34? (a) 2100 (b) 210 (c) 21000
  22. 22.Best estimate of 78 × 28? (a) 24000 (b) 2400 (c) 240
  23. 23.Best estimate of 411 + 136? (a) 300 (b) 500 (c) 700
  24. 24.Best estimate of 33 × 57? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 96 × 84? (a) 80000 (b) 8000 (c) 800
  26. 26.Best estimate of 532 + 405? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 82 × 21? (a) 1600 (b) 16000 (c) 160
  28. 28.Best estimate of 70 × 21? (a) 14000 (b) 1400 (c) 140
  29. 29.Best estimate of 527 + 842? (a) 1300 (b) 1100 (c) 1500
  30. 30.Best estimate of 26 × 63? (a) 1800 (b) 180 (c) 18000
  31. 31.Best estimate of 302 + 848? (a) 900 (b) 1300 (c) 1100
  32. 32.Best estimate of 81 × 39? (a) 32000 (b) 320 (c) 3200
  33. 33.Best estimate of 78 × 57? (a) 480 (b) 48000 (c) 4800
  34. 34.Best estimate of 595 + 614? (a) 1000 (b) 1400 (c) 1200
  35. 35.Best estimate of 706 + 751? (a) 1300 (b) 1500 (c) 1700
  36. 36.Best estimate of 12 × 71? (a) 7000 (b) 700 (c) 70
  37. 37.Best estimate of 73 × 16? (a) 1400 (b) 14000 (c) 140
  38. 38.Best estimate of 57 × 78? (a) 480 (b) 4800 (c) 48000
  39. 39.Best estimate of 16 × 69? (a) 14000 (b) 140 (c) 1400
  40. 40.Best estimate of 512 + 875? (a) 1400 (b) 1600 (c) 1200

Answer key

  1. 800
  2. 600
  3. 4000
  4. 1000
  5. 1000
  6. 800
  7. 2500
  8. 400
  9. 2400
  10. 4500
  11. 2100
  12. 4200
  13. 500
  14. 2700
  15. 1200
  16. 900
  17. 700
  18. 1100
  19. 5400
  20. 600
  21. 2100
  22. 2400
  23. 500
  24. 1800
  25. 8000
  26. 900
  27. 1600
  28. 1400
  29. 1300
  30. 1800
  31. 1100
  32. 3200
  33. 4800
  34. 1200
  35. 1500
  36. 700
  37. 1400
  38. 4800
  39. 1400
  40. 1400

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