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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 654 · 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 32 × 12? (a) 300 (b) 30 (c) 3000
  2. 2.Best estimate of 18 × 80? (a) 160 (b) 16000 (c) 1600
  3. 3.Best estimate of 96 × 31? (a) 3000 (b) 300 (c) 30000
  4. 4.Best estimate of 90 × 76? (a) 7200 (b) 72000 (c) 720
  5. 5.Best estimate of 321 + 477? (a) 800 (b) 1000 (c) 600
  6. 6.Best estimate of 610 + 810? (a) 1200 (b) 1400 (c) 1600
  7. 7.Best estimate of 298 + 351? (a) 700 (b) 900 (c) 500
  8. 8.Best estimate of 24 × 51? (a) 1000 (b) 100 (c) 10000
  9. 9.Best estimate of 47 × 50? (a) 2500 (b) 250 (c) 25000
  10. 10.Best estimate of 632 + 454? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 16 × 76? (a) 160 (b) 16000 (c) 1600
  12. 12.Best estimate of 16 × 47? (a) 1000 (b) 10000 (c) 100
  13. 13.Best estimate of 456 + 328? (a) 800 (b) 1000 (c) 600
  14. 14.Best estimate of 542 + 364? (a) 700 (b) 1100 (c) 900
  15. 15.Best estimate of 89 × 36? (a) 3600 (b) 36000 (c) 360
  16. 16.Best estimate of 94 × 48? (a) 450 (b) 45000 (c) 4500
  17. 17.Best estimate of 88 × 36? (a) 36000 (b) 360 (c) 3600
  18. 18.Best estimate of 47 × 74? (a) 3500 (b) 35000 (c) 350
  19. 19.Best estimate of 449 + 408? (a) 1000 (b) 600 (c) 800
  20. 20.Best estimate of 20 × 71? (a) 14000 (b) 1400 (c) 140
  21. 21.Best estimate of 596 + 502? (a) 1300 (b) 1100 (c) 900
  22. 22.Best estimate of 673 + 797? (a) 1500 (b) 1700 (c) 1300
  23. 23.Best estimate of 72 × 72? (a) 490 (b) 49000 (c) 4900
  24. 24.Best estimate of 12 × 34? (a) 300 (b) 3000 (c) 30
  25. 25.Best estimate of 89 × 49? (a) 450 (b) 45000 (c) 4500
  26. 26.Best estimate of 197 + 204? (a) 600 (b) 400 (c) 200
  27. 27.Best estimate of 677 + 278? (a) 800 (b) 1200 (c) 1000
  28. 28.Best estimate of 96 × 18? (a) 2000 (b) 20000 (c) 200
  29. 29.Best estimate of 760 + 241? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 566 + 517? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 237 + 737? (a) 900 (b) 1100 (c) 700
  32. 32.Best estimate of 92 × 91? (a) 81000 (b) 8100 (c) 810
  33. 33.Best estimate of 69 × 98? (a) 7000 (b) 700 (c) 70000
  34. 34.Best estimate of 854 + 249? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 78 × 43? (a) 32000 (b) 3200 (c) 320
  36. 36.Best estimate of 635 + 307? (a) 1100 (b) 900 (c) 700
  37. 37.Best estimate of 92 × 26? (a) 2700 (b) 27000 (c) 270
  38. 38.Best estimate of 70 × 84? (a) 5600 (b) 560 (c) 56000
  39. 39.Best estimate of 79 × 67? (a) 5600 (b) 56000 (c) 560
  40. 40.Best estimate of 273 + 236? (a) 300 (b) 500 (c) 700

Answer key

  1. 300
  2. 1600
  3. 3000
  4. 7200
  5. 800
  6. 1400
  7. 700
  8. 1000
  9. 2500
  10. 1100
  11. 1600
  12. 1000
  13. 800
  14. 900
  15. 3600
  16. 4500
  17. 3600
  18. 3500
  19. 800
  20. 1400
  21. 1100
  22. 1500
  23. 4900
  24. 300
  25. 4500
  26. 400
  27. 1000
  28. 2000
  29. 1000
  30. 1100
  31. 900
  32. 8100
  33. 7000
  34. 1100
  35. 3200
  36. 900
  37. 2700
  38. 5600
  39. 5600
  40. 500

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