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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 483 · 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 36 × 61? (a) 2400 (b) 24000 (c) 240
  2. 2.Best estimate of 519 + 532? (a) 1200 (b) 800 (c) 1000
  3. 3.Best estimate of 92 × 20? (a) 180 (b) 1800 (c) 18000
  4. 4.Best estimate of 335 + 141? (a) 400 (b) 600 (c) 200
  5. 5.Best estimate of 30 × 90? (a) 2700 (b) 27000 (c) 270
  6. 6.Best estimate of 39 × 42? (a) 1600 (b) 16000 (c) 160
  7. 7.Best estimate of 407 + 314? (a) 900 (b) 700 (c) 500
  8. 8.Best estimate of 40 × 66? (a) 2800 (b) 280 (c) 28000
  9. 9.Best estimate of 36 × 58? (a) 24000 (b) 240 (c) 2400
  10. 10.Best estimate of 21 × 92? (a) 18000 (b) 180 (c) 1800
  11. 11.Best estimate of 69 × 81? (a) 56000 (b) 5600 (c) 560
  12. 12.Best estimate of 316 + 772? (a) 1300 (b) 900 (c) 1100
  13. 13.Best estimate of 189 + 430? (a) 800 (b) 600 (c) 400
  14. 14.Best estimate of 50 × 74? (a) 35000 (b) 3500 (c) 350
  15. 15.Best estimate of 28 × 20? (a) 600 (b) 60 (c) 6000
  16. 16.Best estimate of 57 × 56? (a) 360 (b) 3600 (c) 36000
  17. 17.Best estimate of 46 × 57? (a) 300 (b) 3000 (c) 30000
  18. 18.Best estimate of 36 × 37? (a) 16000 (b) 160 (c) 1600
  19. 19.Best estimate of 841 + 132? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 570 + 692? (a) 1300 (b) 1500 (c) 1100
  21. 21.Best estimate of 187 + 614? (a) 1000 (b) 600 (c) 800
  22. 22.Best estimate of 47 × 31? (a) 15000 (b) 1500 (c) 150
  23. 23.Best estimate of 133 + 435? (a) 700 (b) 500 (c) 300
  24. 24.Best estimate of 82 × 74? (a) 56000 (b) 560 (c) 5600
  25. 25.Best estimate of 288 + 304? (a) 400 (b) 800 (c) 600
  26. 26.Best estimate of 149 + 492? (a) 800 (b) 400 (c) 600
  27. 27.Best estimate of 555 + 693? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 19 × 96? (a) 20000 (b) 200 (c) 2000
  29. 29.Best estimate of 290 + 638? (a) 700 (b) 1100 (c) 900
  30. 30.Best estimate of 366 + 309? (a) 700 (b) 500 (c) 900
  31. 31.Best estimate of 49 × 71? (a) 3500 (b) 35000 (c) 350
  32. 32.Best estimate of 255 + 318? (a) 600 (b) 800 (c) 400
  33. 33.Best estimate of 13 × 23? (a) 2000 (b) 20 (c) 200
  34. 34.Best estimate of 835 + 644? (a) 1400 (b) 1200 (c) 1600
  35. 35.Best estimate of 436 + 802? (a) 1000 (b) 1200 (c) 1400
  36. 36.Best estimate of 135 + 699? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 37 × 32? (a) 1200 (b) 120 (c) 12000
  38. 38.Best estimate of 51 × 56? (a) 3000 (b) 300 (c) 30000
  39. 39.Best estimate of 18 × 56? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 23 × 59? (a) 12000 (b) 120 (c) 1200

Answer key

  1. 2400
  2. 1000
  3. 1800
  4. 400
  5. 2700
  6. 1600
  7. 700
  8. 2800
  9. 2400
  10. 1800
  11. 5600
  12. 1100
  13. 600
  14. 3500
  15. 600
  16. 3600
  17. 3000
  18. 1600
  19. 900
  20. 1300
  21. 800
  22. 1500
  23. 500
  24. 5600
  25. 600
  26. 600
  27. 1300
  28. 2000
  29. 900
  30. 700
  31. 3500
  32. 600
  33. 200
  34. 1400
  35. 1200
  36. 800
  37. 1200
  38. 3000
  39. 1200
  40. 1200

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