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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 318 · 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 87 × 73? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 270 + 122? (a) 400 (b) 200 (c) 600
  3. 3.Best estimate of 42 × 43? (a) 1600 (b) 160 (c) 16000
  4. 4.Best estimate of 88 × 22? (a) 18000 (b) 180 (c) 1800
  5. 5.Best estimate of 321 + 246? (a) 500 (b) 700 (c) 300
  6. 6.Best estimate of 452 + 157? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 44 × 44? (a) 160 (b) 1600 (c) 16000
  8. 8.Best estimate of 304 + 857? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 28 × 79? (a) 240 (b) 2400 (c) 24000
  10. 10.Best estimate of 289 + 180? (a) 500 (b) 700 (c) 300
  11. 11.Best estimate of 32 × 72? (a) 21000 (b) 2100 (c) 210
  12. 12.Best estimate of 22 × 26? (a) 60 (b) 600 (c) 6000
  13. 13.Best estimate of 80 × 46? (a) 400 (b) 40000 (c) 4000
  14. 14.Best estimate of 23 × 51? (a) 100 (b) 10000 (c) 1000
  15. 15.Best estimate of 71 × 19? (a) 1400 (b) 14000 (c) 140
  16. 16.Best estimate of 12 × 22? (a) 2000 (b) 200 (c) 20
  17. 17.Best estimate of 139 + 261? (a) 600 (b) 400 (c) 200
  18. 18.Best estimate of 770 + 469? (a) 1300 (b) 1500 (c) 1100
  19. 19.Best estimate of 84 × 33? (a) 24000 (b) 240 (c) 2400
  20. 20.Best estimate of 160 + 590? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 209 + 589? (a) 800 (b) 600 (c) 1000
  22. 22.Best estimate of 553 + 711? (a) 1300 (b) 1100 (c) 1500
  23. 23.Best estimate of 448 + 216? (a) 600 (b) 800 (c) 400
  24. 24.Best estimate of 216 + 194? (a) 400 (b) 600 (c) 200
  25. 25.Best estimate of 724 + 681? (a) 1400 (b) 1600 (c) 1200
  26. 26.Best estimate of 16 × 56? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 841 + 715? (a) 1500 (b) 1700 (c) 1300
  28. 28.Best estimate of 20 × 16? (a) 400 (b) 40 (c) 4000
  29. 29.Best estimate of 217 + 297? (a) 700 (b) 300 (c) 500
  30. 30.Best estimate of 681 + 404? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 70 × 68? (a) 49000 (b) 490 (c) 4900
  32. 32.Best estimate of 630 + 381? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 74 × 71? (a) 490 (b) 49000 (c) 4900
  34. 34.Best estimate of 82 × 16? (a) 1600 (b) 160 (c) 16000
  35. 35.Best estimate of 352 + 351? (a) 800 (b) 600 (c) 1000
  36. 36.Best estimate of 16 × 33? (a) 6000 (b) 60 (c) 600
  37. 37.Best estimate of 205 + 281? (a) 700 (b) 300 (c) 500
  38. 38.Best estimate of 278 + 240? (a) 500 (b) 700 (c) 300
  39. 39.Best estimate of 31 × 36? (a) 1200 (b) 12000 (c) 120
  40. 40.Best estimate of 23 × 34? (a) 60 (b) 600 (c) 6000

Answer key

  1. 6300
  2. 400
  3. 1600
  4. 1800
  5. 500
  6. 700
  7. 1600
  8. 1200
  9. 2400
  10. 500
  11. 2100
  12. 600
  13. 4000
  14. 1000
  15. 1400
  16. 200
  17. 400
  18. 1300
  19. 2400
  20. 800
  21. 800
  22. 1300
  23. 600
  24. 400
  25. 1400
  26. 1200
  27. 1500
  28. 400
  29. 500
  30. 1100
  31. 4900
  32. 1000
  33. 4900
  34. 1600
  35. 800
  36. 600
  37. 500
  38. 500
  39. 1200
  40. 600

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