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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 101 · 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 585 + 467? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 846 + 154? (a) 800 (b) 1200 (c) 1000
  3. 3.Best estimate of 820 + 778? (a) 1400 (b) 1600 (c) 1800
  4. 4.Best estimate of 318 + 147? (a) 600 (b) 200 (c) 400
  5. 5.Best estimate of 835 + 826? (a) 1800 (b) 1600 (c) 1400
  6. 6.Best estimate of 26 × 58? (a) 18000 (b) 180 (c) 1800
  7. 7.Best estimate of 18 × 87? (a) 18000 (b) 1800 (c) 180
  8. 8.Best estimate of 151 + 644? (a) 600 (b) 800 (c) 1000
  9. 9.Best estimate of 159 + 174? (a) 400 (b) 200 (c) 600
  10. 10.Best estimate of 19 × 42? (a) 80 (b) 800 (c) 8000
  11. 11.Best estimate of 575 + 189? (a) 600 (b) 1000 (c) 800
  12. 12.Best estimate of 713 + 132? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 565 + 444? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 723 + 360? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 567 + 470? (a) 1100 (b) 900 (c) 1300
  16. 16.Best estimate of 464 + 402? (a) 700 (b) 1100 (c) 900
  17. 17.Best estimate of 29 × 86? (a) 2700 (b) 270 (c) 27000
  18. 18.Best estimate of 72 × 16? (a) 14000 (b) 140 (c) 1400
  19. 19.Best estimate of 42 × 69? (a) 2800 (b) 28000 (c) 280
  20. 20.Best estimate of 43 × 80? (a) 32000 (b) 3200 (c) 320
  21. 21.Best estimate of 702 + 870? (a) 1600 (b) 1400 (c) 1800
  22. 22.Best estimate of 74 × 88? (a) 6300 (b) 63000 (c) 630
  23. 23.Best estimate of 93 × 42? (a) 360 (b) 3600 (c) 36000
  24. 24.Best estimate of 90 × 64? (a) 5400 (b) 540 (c) 54000
  25. 25.Best estimate of 81 × 19? (a) 160 (b) 16000 (c) 1600
  26. 26.Best estimate of 84 × 28? (a) 240 (b) 24000 (c) 2400
  27. 27.Best estimate of 23 × 66? (a) 14000 (b) 1400 (c) 140
  28. 28.Best estimate of 702 + 779? (a) 1300 (b) 1700 (c) 1500
  29. 29.Best estimate of 92 × 67? (a) 630 (b) 6300 (c) 63000
  30. 30.Best estimate of 22 × 41? (a) 8000 (b) 800 (c) 80
  31. 31.Best estimate of 660 + 686? (a) 1400 (b) 1600 (c) 1200
  32. 32.Best estimate of 853 + 467? (a) 1400 (b) 1600 (c) 1200
  33. 33.Best estimate of 26 × 57? (a) 18000 (b) 180 (c) 1800
  34. 34.Best estimate of 272 + 288? (a) 400 (b) 800 (c) 600
  35. 35.Best estimate of 598 + 384? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 285 + 228? (a) 500 (b) 700 (c) 300
  37. 37.Best estimate of 26 × 51? (a) 15000 (b) 1500 (c) 150
  38. 38.Best estimate of 699 + 209? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 16 × 41? (a) 800 (b) 8000 (c) 80
  40. 40.Best estimate of 216 + 258? (a) 700 (b) 500 (c) 300

Answer key

  1. 1100
  2. 1000
  3. 1600
  4. 400
  5. 1600
  6. 1800
  7. 1800
  8. 800
  9. 400
  10. 800
  11. 800
  12. 800
  13. 1000
  14. 1100
  15. 1100
  16. 900
  17. 2700
  18. 1400
  19. 2800
  20. 3200
  21. 1600
  22. 6300
  23. 3600
  24. 5400
  25. 1600
  26. 2400
  27. 1400
  28. 1500
  29. 6300
  30. 800
  31. 1400
  32. 1400
  33. 1800
  34. 600
  35. 1000
  36. 500
  37. 1500
  38. 900
  39. 800
  40. 500

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