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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 146 · 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 88 × 80? (a) 72000 (b) 7200 (c) 720
  2. 2.Best estimate of 26 × 76? (a) 240 (b) 24000 (c) 2400
  3. 3.Best estimate of 299 + 799? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 209 + 561? (a) 600 (b) 1000 (c) 800
  5. 5.Best estimate of 47 × 84? (a) 4000 (b) 400 (c) 40000
  6. 6.Best estimate of 762 + 724? (a) 1300 (b) 1700 (c) 1500
  7. 7.Best estimate of 560 + 730? (a) 1300 (b) 1500 (c) 1100
  8. 8.Best estimate of 799 + 722? (a) 1300 (b) 1500 (c) 1700
  9. 9.Best estimate of 245 + 808? (a) 800 (b) 1000 (c) 1200
  10. 10.Best estimate of 57 × 23? (a) 12000 (b) 1200 (c) 120
  11. 11.Best estimate of 44 × 96? (a) 40000 (b) 400 (c) 4000
  12. 12.Best estimate of 516 + 188? (a) 700 (b) 900 (c) 500
  13. 13.Best estimate of 86 × 14? (a) 900 (b) 9000 (c) 90
  14. 14.Best estimate of 29 × 56? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 297 + 565? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 598 + 659? (a) 1300 (b) 1500 (c) 1100
  17. 17.Best estimate of 41 × 20? (a) 80 (b) 8000 (c) 800
  18. 18.Best estimate of 91 × 87? (a) 810 (b) 81000 (c) 8100
  19. 19.Best estimate of 37 × 17? (a) 8000 (b) 800 (c) 80
  20. 20.Best estimate of 48 × 18? (a) 10000 (b) 1000 (c) 100
  21. 21.Best estimate of 34 × 96? (a) 300 (b) 3000 (c) 30000
  22. 22.Best estimate of 300 + 433? (a) 700 (b) 500 (c) 900
  23. 23.Best estimate of 231 + 718? (a) 1100 (b) 700 (c) 900
  24. 24.Best estimate of 21 × 93? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 26 × 44? (a) 1200 (b) 12000 (c) 120
  26. 26.Best estimate of 851 + 277? (a) 1200 (b) 1000 (c) 1400
  27. 27.Best estimate of 68 × 98? (a) 700 (b) 7000 (c) 70000
  28. 28.Best estimate of 404 + 479? (a) 1100 (b) 700 (c) 900
  29. 29.Best estimate of 700 + 328? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 425 + 291? (a) 700 (b) 900 (c) 500
  31. 31.Best estimate of 162 + 839? (a) 1000 (b) 800 (c) 1200
  32. 32.Best estimate of 29 × 52? (a) 150 (b) 1500 (c) 15000
  33. 33.Best estimate of 653 + 561? (a) 1100 (b) 1300 (c) 1500
  34. 34.Best estimate of 157 + 236? (a) 600 (b) 400 (c) 200
  35. 35.Best estimate of 61 × 23? (a) 12000 (b) 1200 (c) 120
  36. 36.Best estimate of 76 × 32? (a) 24000 (b) 2400 (c) 240
  37. 37.Best estimate of 89 × 56? (a) 5400 (b) 54000 (c) 540
  38. 38.Best estimate of 634 + 136? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 209 + 167? (a) 400 (b) 200 (c) 600
  40. 40.Best estimate of 27 × 38? (a) 120 (b) 1200 (c) 12000

Answer key

  1. 7200
  2. 2400
  3. 1100
  4. 800
  5. 4000
  6. 1500
  7. 1300
  8. 1500
  9. 1000
  10. 1200
  11. 4000
  12. 700
  13. 900
  14. 1800
  15. 900
  16. 1300
  17. 800
  18. 8100
  19. 800
  20. 1000
  21. 3000
  22. 700
  23. 900
  24. 1800
  25. 1200
  26. 1200
  27. 7000
  28. 900
  29. 1000
  30. 700
  31. 1000
  32. 1500
  33. 1300
  34. 400
  35. 1200
  36. 2400
  37. 5400
  38. 700
  39. 400
  40. 1200

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