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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 828 · 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 843 + 557? (a) 1400 (b) 1200 (c) 1600
  2. 2.Best estimate of 286 + 156? (a) 700 (b) 300 (c) 500
  3. 3.Best estimate of 637 + 614? (a) 1000 (b) 1400 (c) 1200
  4. 4.Best estimate of 41 × 52? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 54 × 36? (a) 20000 (b) 2000 (c) 200
  6. 6.Best estimate of 16 × 37? (a) 800 (b) 80 (c) 8000
  7. 7.Best estimate of 280 + 326? (a) 800 (b) 600 (c) 400
  8. 8.Best estimate of 566 + 140? (a) 500 (b) 900 (c) 700
  9. 9.Best estimate of 798 + 458? (a) 1100 (b) 1500 (c) 1300
  10. 10.Best estimate of 17 × 52? (a) 1000 (b) 100 (c) 10000
  11. 11.Best estimate of 13 × 44? (a) 4000 (b) 40 (c) 400
  12. 12.Best estimate of 63 × 90? (a) 5400 (b) 54000 (c) 540
  13. 13.Best estimate of 257 + 218? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 77 × 44? (a) 320 (b) 32000 (c) 3200
  15. 15.Best estimate of 751 + 468? (a) 1100 (b) 1500 (c) 1300
  16. 16.Best estimate of 549 + 865? (a) 1600 (b) 1200 (c) 1400
  17. 17.Best estimate of 30 × 67? (a) 210 (b) 2100 (c) 21000
  18. 18.Best estimate of 83 × 76? (a) 64000 (b) 640 (c) 6400
  19. 19.Best estimate of 81 × 56? (a) 480 (b) 4800 (c) 48000
  20. 20.Best estimate of 325 + 190? (a) 700 (b) 300 (c) 500
  21. 21.Best estimate of 92 × 93? (a) 8100 (b) 81000 (c) 810
  22. 22.Best estimate of 385 + 656? (a) 900 (b) 1100 (c) 1300
  23. 23.Best estimate of 37 × 27? (a) 1200 (b) 120 (c) 12000
  24. 24.Best estimate of 759 + 522? (a) 1300 (b) 1100 (c) 1500
  25. 25.Best estimate of 429 + 512? (a) 1100 (b) 900 (c) 700
  26. 26.Best estimate of 491 + 313? (a) 600 (b) 1000 (c) 800
  27. 27.Best estimate of 33 × 52? (a) 1500 (b) 150 (c) 15000
  28. 28.Best estimate of 33 × 79? (a) 2400 (b) 240 (c) 24000
  29. 29.Best estimate of 823 + 491? (a) 1500 (b) 1100 (c) 1300
  30. 30.Best estimate of 47 × 27? (a) 1500 (b) 150 (c) 15000
  31. 31.Best estimate of 84 × 12? (a) 800 (b) 8000 (c) 80
  32. 32.Best estimate of 242 + 713? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 505 + 249? (a) 700 (b) 900 (c) 500
  34. 34.Best estimate of 40 × 40? (a) 160 (b) 16000 (c) 1600
  35. 35.Best estimate of 780 + 797? (a) 1800 (b) 1400 (c) 1600
  36. 36.Best estimate of 703 + 640? (a) 1300 (b) 1100 (c) 1500
  37. 37.Best estimate of 64 × 52? (a) 30000 (b) 3000 (c) 300
  38. 38.Best estimate of 794 + 206? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 813 + 403? (a) 1400 (b) 1000 (c) 1200
  40. 40.Best estimate of 46 × 20? (a) 10000 (b) 1000 (c) 100

Answer key

  1. 1400
  2. 500
  3. 1200
  4. 2000
  5. 2000
  6. 800
  7. 600
  8. 700
  9. 1300
  10. 1000
  11. 400
  12. 5400
  13. 500
  14. 3200
  15. 1300
  16. 1400
  17. 2100
  18. 6400
  19. 4800
  20. 500
  21. 8100
  22. 1100
  23. 1200
  24. 1300
  25. 900
  26. 800
  27. 1500
  28. 2400
  29. 1300
  30. 1500
  31. 800
  32. 900
  33. 700
  34. 1600
  35. 1600
  36. 1300
  37. 3000
  38. 1000
  39. 1200
  40. 1000

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