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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 172 · 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 274 + 210? (a) 300 (b) 500 (c) 700
  2. 2.Best estimate of 74 × 56? (a) 4200 (b) 420 (c) 42000
  3. 3.Best estimate of 18 × 16? (a) 4000 (b) 40 (c) 400
  4. 4.Best estimate of 32 × 14? (a) 30 (b) 3000 (c) 300
  5. 5.Best estimate of 212 + 802? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 386 + 267? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 179 + 329? (a) 300 (b) 500 (c) 700
  8. 8.Best estimate of 33 × 28? (a) 9000 (b) 900 (c) 90
  9. 9.Best estimate of 56 × 90? (a) 540 (b) 54000 (c) 5400
  10. 10.Best estimate of 24 × 80? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 33 × 88? (a) 27000 (b) 270 (c) 2700
  12. 12.Best estimate of 171 + 551? (a) 600 (b) 1000 (c) 800
  13. 13.Best estimate of 69 × 13? (a) 700 (b) 70 (c) 7000
  14. 14.Best estimate of 600 + 702? (a) 1100 (b) 1500 (c) 1300
  15. 15.Best estimate of 225 + 400? (a) 400 (b) 800 (c) 600
  16. 16.Best estimate of 819 + 430? (a) 1000 (b) 1400 (c) 1200
  17. 17.Best estimate of 239 + 638? (a) 800 (b) 1000 (c) 600
  18. 18.Best estimate of 59 × 96? (a) 6000 (b) 600 (c) 60000
  19. 19.Best estimate of 325 + 580? (a) 900 (b) 700 (c) 1100
  20. 20.Best estimate of 71 × 26? (a) 21000 (b) 210 (c) 2100
  21. 21.Best estimate of 16 × 51? (a) 1000 (b) 10000 (c) 100
  22. 22.Best estimate of 64 × 92? (a) 54000 (b) 5400 (c) 540
  23. 23.Best estimate of 94 × 78? (a) 72000 (b) 720 (c) 7200
  24. 24.Best estimate of 18 × 23? (a) 4000 (b) 40 (c) 400
  25. 25.Best estimate of 434 + 448? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 255 + 413? (a) 700 (b) 500 (c) 900
  27. 27.Best estimate of 200 + 532? (a) 900 (b) 700 (c) 500
  28. 28.Best estimate of 311 + 849? (a) 1100 (b) 900 (c) 1300
  29. 29.Best estimate of 852 + 285? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 399 + 739? (a) 1100 (b) 1300 (c) 900
  31. 31.Best estimate of 86 × 88? (a) 810 (b) 81000 (c) 8100
  32. 32.Best estimate of 18 × 61? (a) 1200 (b) 12000 (c) 120
  33. 33.Best estimate of 465 + 829? (a) 1300 (b) 1100 (c) 1500
  34. 34.Best estimate of 30 × 14? (a) 300 (b) 3000 (c) 30
  35. 35.Best estimate of 33 × 86? (a) 27000 (b) 270 (c) 2700
  36. 36.Best estimate of 692 + 288? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 40 × 48? (a) 2000 (b) 20000 (c) 200
  38. 38.Best estimate of 678 + 567? (a) 1300 (b) 1100 (c) 1500
  39. 39.Best estimate of 807 + 811? (a) 1600 (b) 1800 (c) 1400
  40. 40.Best estimate of 313 + 487? (a) 800 (b) 600 (c) 1000

Answer key

  1. 500
  2. 4200
  3. 400
  4. 300
  5. 1000
  6. 700
  7. 500
  8. 900
  9. 5400
  10. 1600
  11. 2700
  12. 800
  13. 700
  14. 1300
  15. 600
  16. 1200
  17. 800
  18. 6000
  19. 900
  20. 2100
  21. 1000
  22. 5400
  23. 7200
  24. 400
  25. 800
  26. 700
  27. 700
  28. 1100
  29. 1200
  30. 1100
  31. 8100
  32. 1200
  33. 1300
  34. 300
  35. 2700
  36. 1000
  37. 2000
  38. 1300
  39. 1600
  40. 800

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