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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 19 · 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 93 × 66? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 84 × 18? (a) 160 (b) 1600 (c) 16000
  3. 3.Best estimate of 207 + 643? (a) 1000 (b) 600 (c) 800
  4. 4.Best estimate of 829 + 251? (a) 1300 (b) 900 (c) 1100
  5. 5.Best estimate of 33 × 26? (a) 90 (b) 900 (c) 9000
  6. 6.Best estimate of 577 + 682? (a) 1300 (b) 1500 (c) 1100
  7. 7.Best estimate of 37 × 68? (a) 28000 (b) 280 (c) 2800
  8. 8.Best estimate of 333 + 657? (a) 800 (b) 1000 (c) 1200
  9. 9.Best estimate of 851 + 330? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 189 + 600? (a) 600 (b) 1000 (c) 800
  11. 11.Best estimate of 811 + 332? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 19 × 97? (a) 200 (b) 20000 (c) 2000
  13. 13.Best estimate of 51 × 26? (a) 15000 (b) 1500 (c) 150
  14. 14.Best estimate of 333 + 770? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 30 × 19? (a) 60 (b) 600 (c) 6000
  16. 16.Best estimate of 124 + 320? (a) 600 (b) 400 (c) 200
  17. 17.Best estimate of 267 + 782? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 14 × 42? (a) 40 (b) 400 (c) 4000
  19. 19.Best estimate of 502 + 182? (a) 500 (b) 900 (c) 700
  20. 20.Best estimate of 326 + 737? (a) 800 (b) 1000 (c) 1200
  21. 21.Best estimate of 68 × 63? (a) 4200 (b) 420 (c) 42000
  22. 22.Best estimate of 44 × 23? (a) 8000 (b) 800 (c) 80
  23. 23.Best estimate of 329 + 653? (a) 1200 (b) 1000 (c) 800
  24. 24.Best estimate of 86 × 98? (a) 900 (b) 90000 (c) 9000
  25. 25.Best estimate of 76 × 12? (a) 8000 (b) 800 (c) 80
  26. 26.Best estimate of 52 × 96? (a) 5000 (b) 50000 (c) 500
  27. 27.Best estimate of 347 + 591? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 305 + 185? (a) 700 (b) 300 (c) 500
  29. 29.Best estimate of 229 + 619? (a) 600 (b) 800 (c) 1000
  30. 30.Best estimate of 72 × 21? (a) 1400 (b) 140 (c) 14000
  31. 31.Best estimate of 51 × 58? (a) 3000 (b) 300 (c) 30000
  32. 32.Best estimate of 31 × 94? (a) 2700 (b) 270 (c) 27000
  33. 33.Best estimate of 33 × 79? (a) 2400 (b) 240 (c) 24000
  34. 34.Best estimate of 77 × 72? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 199 + 304? (a) 500 (b) 700 (c) 300
  36. 36.Best estimate of 41 × 29? (a) 12000 (b) 120 (c) 1200
  37. 37.Best estimate of 740 + 401? (a) 900 (b) 1300 (c) 1100
  38. 38.Best estimate of 393 + 370? (a) 1000 (b) 600 (c) 800
  39. 39.Best estimate of 58 × 17? (a) 12000 (b) 1200 (c) 120
  40. 40.Best estimate of 56 × 37? (a) 24000 (b) 2400 (c) 240

Answer key

  1. 6300
  2. 1600
  3. 800
  4. 1100
  5. 900
  6. 1300
  7. 2800
  8. 1000
  9. 1200
  10. 800
  11. 1100
  12. 2000
  13. 1500
  14. 1100
  15. 600
  16. 400
  17. 1100
  18. 400
  19. 700
  20. 1000
  21. 4200
  22. 800
  23. 1000
  24. 9000
  25. 800
  26. 5000
  27. 900
  28. 500
  29. 800
  30. 1400
  31. 3000
  32. 2700
  33. 2400
  34. 5600
  35. 500
  36. 1200
  37. 1100
  38. 800
  39. 1200
  40. 2400

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