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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 216 · 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 434 + 298? (a) 500 (b) 900 (c) 700
  2. 2.Best estimate of 19 × 51? (a) 100 (b) 10000 (c) 1000
  3. 3.Best estimate of 22 × 78? (a) 160 (b) 16000 (c) 1600
  4. 4.Best estimate of 98 × 78? (a) 8000 (b) 800 (c) 80000
  5. 5.Best estimate of 16 × 56? (a) 12000 (b) 1200 (c) 120
  6. 6.Best estimate of 70 × 42? (a) 2800 (b) 280 (c) 28000
  7. 7.Best estimate of 60 × 72? (a) 42000 (b) 420 (c) 4200
  8. 8.Best estimate of 366 + 584? (a) 1000 (b) 800 (c) 1200
  9. 9.Best estimate of 583 + 262? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 13 × 29? (a) 300 (b) 3000 (c) 30
  11. 11.Best estimate of 36 × 70? (a) 280 (b) 2800 (c) 28000
  12. 12.Best estimate of 29 × 36? (a) 12000 (b) 1200 (c) 120
  13. 13.Best estimate of 42 × 33? (a) 1200 (b) 12000 (c) 120
  14. 14.Best estimate of 18 × 60? (a) 1200 (b) 12000 (c) 120
  15. 15.Best estimate of 59 × 26? (a) 180 (b) 1800 (c) 18000
  16. 16.Best estimate of 815 + 155? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 457 + 211? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 329 + 471? (a) 600 (b) 800 (c) 1000
  19. 19.Best estimate of 51 × 23? (a) 1000 (b) 10000 (c) 100
  20. 20.Best estimate of 228 + 710? (a) 1100 (b) 700 (c) 900
  21. 21.Best estimate of 151 + 867? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 738 + 238? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 390 + 200? (a) 600 (b) 400 (c) 800
  24. 24.Best estimate of 494 + 397? (a) 900 (b) 1100 (c) 700
  25. 25.Best estimate of 96 × 43? (a) 4000 (b) 400 (c) 40000
  26. 26.Best estimate of 20 × 26? (a) 6000 (b) 60 (c) 600
  27. 27.Best estimate of 49 × 60? (a) 3000 (b) 30000 (c) 300
  28. 28.Best estimate of 265 + 397? (a) 700 (b) 500 (c) 900
  29. 29.Best estimate of 63 × 17? (a) 12000 (b) 1200 (c) 120
  30. 30.Best estimate of 76 × 64? (a) 4800 (b) 48000 (c) 480
  31. 31.Best estimate of 24 × 86? (a) 1800 (b) 18000 (c) 180
  32. 32.Best estimate of 97 × 18? (a) 200 (b) 20000 (c) 2000
  33. 33.Best estimate of 70 × 68? (a) 4900 (b) 490 (c) 49000
  34. 34.Best estimate of 23 × 17? (a) 4000 (b) 400 (c) 40
  35. 35.Best estimate of 47 × 17? (a) 100 (b) 10000 (c) 1000
  36. 36.Best estimate of 87 × 19? (a) 180 (b) 1800 (c) 18000
  37. 37.Best estimate of 21 × 29? (a) 6000 (b) 600 (c) 60
  38. 38.Best estimate of 255 + 312? (a) 400 (b) 800 (c) 600
  39. 39.Best estimate of 71 × 33? (a) 21000 (b) 2100 (c) 210
  40. 40.Best estimate of 777 + 722? (a) 1300 (b) 1500 (c) 1700

Answer key

  1. 700
  2. 1000
  3. 1600
  4. 8000
  5. 1200
  6. 2800
  7. 4200
  8. 1000
  9. 900
  10. 300
  11. 2800
  12. 1200
  13. 1200
  14. 1200
  15. 1800
  16. 1000
  17. 700
  18. 800
  19. 1000
  20. 900
  21. 1100
  22. 900
  23. 600
  24. 900
  25. 4000
  26. 600
  27. 3000
  28. 700
  29. 1200
  30. 4800
  31. 1800
  32. 2000
  33. 4900
  34. 400
  35. 1000
  36. 1800
  37. 600
  38. 600
  39. 2100
  40. 1500

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