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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 310 · 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 26 × 68? (a) 21000 (b) 210 (c) 2100
  2. 2.Best estimate of 13 × 23? (a) 200 (b) 20 (c) 2000
  3. 3.Best estimate of 17 × 73? (a) 1400 (b) 14000 (c) 140
  4. 4.Best estimate of 247 + 596? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 29 × 50? (a) 1500 (b) 15000 (c) 150
  6. 6.Best estimate of 86 × 98? (a) 90000 (b) 9000 (c) 900
  7. 7.Best estimate of 58 × 89? (a) 5400 (b) 540 (c) 54000
  8. 8.Best estimate of 23 × 13? (a) 200 (b) 20 (c) 2000
  9. 9.Best estimate of 704 + 795? (a) 1500 (b) 1300 (c) 1700
  10. 10.Best estimate of 66 × 42? (a) 28000 (b) 2800 (c) 280
  11. 11.Best estimate of 465 + 431? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 56 × 80? (a) 48000 (b) 4800 (c) 480
  13. 13.Best estimate of 53 × 30? (a) 150 (b) 1500 (c) 15000
  14. 14.Best estimate of 863 + 499? (a) 1600 (b) 1200 (c) 1400
  15. 15.Best estimate of 14 × 21? (a) 200 (b) 2000 (c) 20
  16. 16.Best estimate of 71 × 47? (a) 3500 (b) 350 (c) 35000
  17. 17.Best estimate of 182 + 440? (a) 400 (b) 600 (c) 800
  18. 18.Best estimate of 93 × 91? (a) 8100 (b) 81000 (c) 810
  19. 19.Best estimate of 481 + 802? (a) 1500 (b) 1300 (c) 1100
  20. 20.Best estimate of 598 + 560? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 51 × 57? (a) 3000 (b) 30000 (c) 300
  22. 22.Best estimate of 37 × 26? (a) 1200 (b) 120 (c) 12000
  23. 23.Best estimate of 41 × 92? (a) 36000 (b) 3600 (c) 360
  24. 24.Best estimate of 308 + 585? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 775 + 221? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 268 + 815? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 495 + 191? (a) 700 (b) 900 (c) 500
  28. 28.Best estimate of 755 + 501? (a) 1300 (b) 1100 (c) 1500
  29. 29.Best estimate of 226 + 282? (a) 700 (b) 500 (c) 300
  30. 30.Best estimate of 76 × 38? (a) 32000 (b) 3200 (c) 320
  31. 31.Best estimate of 218 + 151? (a) 200 (b) 400 (c) 600
  32. 32.Best estimate of 556 + 484? (a) 1100 (b) 1300 (c) 900
  33. 33.Best estimate of 64 × 73? (a) 4200 (b) 42000 (c) 420
  34. 34.Best estimate of 74 × 97? (a) 7000 (b) 70000 (c) 700
  35. 35.Best estimate of 68 × 24? (a) 14000 (b) 1400 (c) 140
  36. 36.Best estimate of 696 + 624? (a) 1100 (b) 1500 (c) 1300
  37. 37.Best estimate of 19 × 32? (a) 60 (b) 6000 (c) 600
  38. 38.Best estimate of 31 × 16? (a) 60 (b) 600 (c) 6000
  39. 39.Best estimate of 16 × 86? (a) 18000 (b) 1800 (c) 180
  40. 40.Best estimate of 26 × 96? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 2100
  2. 200
  3. 1400
  4. 800
  5. 1500
  6. 9000
  7. 5400
  8. 200
  9. 1500
  10. 2800
  11. 900
  12. 4800
  13. 1500
  14. 1400
  15. 200
  16. 3500
  17. 600
  18. 8100
  19. 1300
  20. 1200
  21. 3000
  22. 1200
  23. 3600
  24. 900
  25. 1000
  26. 1100
  27. 700
  28. 1300
  29. 500
  30. 3200
  31. 400
  32. 1100
  33. 4200
  34. 7000
  35. 1400
  36. 1300
  37. 600
  38. 600
  39. 1800
  40. 3000

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