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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 584 · 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 82 × 16? (a) 160 (b) 16000 (c) 1600
  2. 2.Best estimate of 692 + 856? (a) 1400 (b) 1800 (c) 1600
  3. 3.Best estimate of 89 × 42? (a) 360 (b) 3600 (c) 36000
  4. 4.Best estimate of 553 + 877? (a) 1700 (b) 1300 (c) 1500
  5. 5.Best estimate of 875 + 787? (a) 1500 (b) 1900 (c) 1700
  6. 6.Best estimate of 48 × 30? (a) 150 (b) 1500 (c) 15000
  7. 7.Best estimate of 68 × 41? (a) 2800 (b) 280 (c) 28000
  8. 8.Best estimate of 492 + 526? (a) 1000 (b) 800 (c) 1200
  9. 9.Best estimate of 713 + 385? (a) 1100 (b) 900 (c) 1300
  10. 10.Best estimate of 507 + 487? (a) 1200 (b) 800 (c) 1000
  11. 11.Best estimate of 637 + 268? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 86 × 50? (a) 45000 (b) 450 (c) 4500
  13. 13.Best estimate of 42 × 41? (a) 160 (b) 16000 (c) 1600
  14. 14.Best estimate of 81 × 17? (a) 1600 (b) 160 (c) 16000
  15. 15.Best estimate of 46 × 51? (a) 2500 (b) 25000 (c) 250
  16. 16.Best estimate of 281 + 609? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 536 + 292? (a) 600 (b) 1000 (c) 800
  18. 18.Best estimate of 506 + 383? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 269 + 863? (a) 1400 (b) 1000 (c) 1200
  20. 20.Best estimate of 26 × 31? (a) 90 (b) 900 (c) 9000
  21. 21.Best estimate of 756 + 466? (a) 1300 (b) 1100 (c) 1500
  22. 22.Best estimate of 220 + 530? (a) 900 (b) 700 (c) 500
  23. 23.Best estimate of 34 × 91? (a) 27000 (b) 270 (c) 2700
  24. 24.Best estimate of 81 × 62? (a) 4800 (b) 48000 (c) 480
  25. 25.Best estimate of 33 × 17? (a) 60 (b) 600 (c) 6000
  26. 26.Best estimate of 67 × 29? (a) 2100 (b) 21000 (c) 210
  27. 27.Best estimate of 132 + 186? (a) 500 (b) 100 (c) 300
  28. 28.Best estimate of 38 × 76? (a) 320 (b) 3200 (c) 32000
  29. 29.Best estimate of 428 + 386? (a) 600 (b) 800 (c) 1000
  30. 30.Best estimate of 12 × 96? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 343 + 446? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 91 × 46? (a) 450 (b) 4500 (c) 45000
  33. 33.Best estimate of 205 + 485? (a) 900 (b) 500 (c) 700
  34. 34.Best estimate of 21 × 60? (a) 12000 (b) 1200 (c) 120
  35. 35.Best estimate of 29 × 46? (a) 15000 (b) 150 (c) 1500
  36. 36.Best estimate of 292 + 344? (a) 400 (b) 800 (c) 600
  37. 37.Best estimate of 84 × 52? (a) 40000 (b) 4000 (c) 400
  38. 38.Best estimate of 22 × 76? (a) 16000 (b) 1600 (c) 160
  39. 39.Best estimate of 16 × 86? (a) 18000 (b) 180 (c) 1800
  40. 40.Best estimate of 362 + 825? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 1600
  2. 1600
  3. 3600
  4. 1500
  5. 1700
  6. 1500
  7. 2800
  8. 1000
  9. 1100
  10. 1000
  11. 900
  12. 4500
  13. 1600
  14. 1600
  15. 2500
  16. 900
  17. 800
  18. 900
  19. 1200
  20. 900
  21. 1300
  22. 700
  23. 2700
  24. 4800
  25. 600
  26. 2100
  27. 300
  28. 3200
  29. 800
  30. 1000
  31. 700
  32. 4500
  33. 700
  34. 1200
  35. 1500
  36. 600
  37. 4000
  38. 1600
  39. 1800
  40. 1200

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