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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 878 · 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 529 + 782? (a) 1300 (b) 1500 (c) 1100
  2. 2.Best estimate of 214 + 278? (a) 700 (b) 300 (c) 500
  3. 3.Best estimate of 548 + 526? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 21 × 76? (a) 160 (b) 16000 (c) 1600
  5. 5.Best estimate of 435 + 222? (a) 600 (b) 800 (c) 400
  6. 6.Best estimate of 14 × 26? (a) 300 (b) 3000 (c) 30
  7. 7.Best estimate of 92 × 86? (a) 81000 (b) 8100 (c) 810
  8. 8.Best estimate of 92 × 49? (a) 450 (b) 45000 (c) 4500
  9. 9.Best estimate of 47 × 14? (a) 500 (b) 5000 (c) 50
  10. 10.Best estimate of 530 + 556? (a) 1100 (b) 900 (c) 1300
  11. 11.Best estimate of 54 × 72? (a) 350 (b) 35000 (c) 3500
  12. 12.Best estimate of 16 × 81? (a) 160 (b) 16000 (c) 1600
  13. 13.Best estimate of 23 × 74? (a) 140 (b) 14000 (c) 1400
  14. 14.Best estimate of 122 + 590? (a) 700 (b) 500 (c) 900
  15. 15.Best estimate of 234 + 265? (a) 700 (b) 500 (c) 300
  16. 16.Best estimate of 59 × 26? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 86 × 47? (a) 45000 (b) 450 (c) 4500
  18. 18.Best estimate of 324 + 800? (a) 1100 (b) 900 (c) 1300
  19. 19.Best estimate of 494 + 610? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 413 + 226? (a) 600 (b) 400 (c) 800
  21. 21.Best estimate of 395 + 657? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 303 + 477? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 497 + 383? (a) 900 (b) 700 (c) 1100
  24. 24.Best estimate of 49 × 96? (a) 5000 (b) 500 (c) 50000
  25. 25.Best estimate of 50 × 23? (a) 1000 (b) 100 (c) 10000
  26. 26.Best estimate of 569 + 163? (a) 1000 (b) 600 (c) 800
  27. 27.Best estimate of 20 × 60? (a) 12000 (b) 1200 (c) 120
  28. 28.Best estimate of 291 + 259? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 53 × 16? (a) 100 (b) 10000 (c) 1000
  30. 30.Best estimate of 57 × 33? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 451 + 417? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 43 × 46? (a) 20000 (b) 200 (c) 2000
  33. 33.Best estimate of 33 × 69? (a) 210 (b) 2100 (c) 21000
  34. 34.Best estimate of 240 + 821? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 76 × 78? (a) 640 (b) 64000 (c) 6400
  36. 36.Best estimate of 124 + 396? (a) 700 (b) 300 (c) 500
  37. 37.Best estimate of 68 × 33? (a) 210 (b) 2100 (c) 21000
  38. 38.Best estimate of 67 × 23? (a) 14000 (b) 1400 (c) 140
  39. 39.Best estimate of 17 × 49? (a) 100 (b) 10000 (c) 1000
  40. 40.Best estimate of 78 × 81? (a) 64000 (b) 640 (c) 6400

Answer key

  1. 1300
  2. 500
  3. 1000
  4. 1600
  5. 600
  6. 300
  7. 8100
  8. 4500
  9. 500
  10. 1100
  11. 3500
  12. 1600
  13. 1400
  14. 700
  15. 500
  16. 1800
  17. 4500
  18. 1100
  19. 1100
  20. 600
  21. 1100
  22. 800
  23. 900
  24. 5000
  25. 1000
  26. 800
  27. 1200
  28. 600
  29. 1000
  30. 1800
  31. 900
  32. 2000
  33. 2100
  34. 1000
  35. 6400
  36. 500
  37. 2100
  38. 1400
  39. 1000
  40. 6400

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