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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 835 · 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 80 × 70? (a) 56000 (b) 560 (c) 5600
  2. 2.Best estimate of 48 × 22? (a) 10000 (b) 100 (c) 1000
  3. 3.Best estimate of 53 × 14? (a) 50 (b) 500 (c) 5000
  4. 4.Best estimate of 357 + 346? (a) 900 (b) 700 (c) 500
  5. 5.Best estimate of 72 × 60? (a) 420 (b) 42000 (c) 4200
  6. 6.Best estimate of 21 × 76? (a) 16000 (b) 160 (c) 1600
  7. 7.Best estimate of 29 × 98? (a) 300 (b) 30000 (c) 3000
  8. 8.Best estimate of 49 × 36? (a) 200 (b) 20000 (c) 2000
  9. 9.Best estimate of 425 + 877? (a) 1300 (b) 1500 (c) 1100
  10. 10.Best estimate of 597 + 270? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 855 + 461? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 16 × 57? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 98 × 73? (a) 7000 (b) 70000 (c) 700
  14. 14.Best estimate of 28 × 70? (a) 2100 (b) 21000 (c) 210
  15. 15.Best estimate of 578 + 275? (a) 700 (b) 1100 (c) 900
  16. 16.Best estimate of 89 × 24? (a) 18000 (b) 180 (c) 1800
  17. 17.Best estimate of 557 + 725? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 661 + 355? (a) 1100 (b) 1300 (c) 900
  19. 19.Best estimate of 81 × 50? (a) 400 (b) 40000 (c) 4000
  20. 20.Best estimate of 580 + 282? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 657 + 323? (a) 1000 (b) 800 (c) 1200
  22. 22.Best estimate of 401 + 823? (a) 1200 (b) 1400 (c) 1000
  23. 23.Best estimate of 369 + 563? (a) 1000 (b) 800 (c) 1200
  24. 24.Best estimate of 228 + 283? (a) 500 (b) 300 (c) 700
  25. 25.Best estimate of 46 × 88? (a) 45000 (b) 450 (c) 4500
  26. 26.Best estimate of 77 × 20? (a) 160 (b) 1600 (c) 16000
  27. 27.Best estimate of 609 + 299? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 71 × 20? (a) 14000 (b) 1400 (c) 140
  29. 29.Best estimate of 291 + 172? (a) 500 (b) 300 (c) 700
  30. 30.Best estimate of 527 + 525? (a) 1000 (b) 800 (c) 1200
  31. 31.Best estimate of 841 + 151? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 612 + 587? (a) 1000 (b) 1200 (c) 1400
  33. 33.Best estimate of 676 + 348? (a) 1200 (b) 1000 (c) 800
  34. 34.Best estimate of 88 × 23? (a) 1800 (b) 180 (c) 18000
  35. 35.Best estimate of 39 × 28? (a) 12000 (b) 1200 (c) 120
  36. 36.Best estimate of 76 × 24? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 56 × 84? (a) 48000 (b) 480 (c) 4800
  38. 38.Best estimate of 43 × 46? (a) 2000 (b) 200 (c) 20000
  39. 39.Best estimate of 78 × 54? (a) 40000 (b) 4000 (c) 400
  40. 40.Best estimate of 87 × 92? (a) 8100 (b) 810 (c) 81000

Answer key

  1. 5600
  2. 1000
  3. 500
  4. 700
  5. 4200
  6. 1600
  7. 3000
  8. 2000
  9. 1300
  10. 900
  11. 1400
  12. 1200
  13. 7000
  14. 2100
  15. 900
  16. 1800
  17. 1300
  18. 1100
  19. 4000
  20. 900
  21. 1000
  22. 1200
  23. 1000
  24. 500
  25. 4500
  26. 1600
  27. 900
  28. 1400
  29. 500
  30. 1000
  31. 1000
  32. 1200
  33. 1000
  34. 1800
  35. 1200
  36. 1600
  37. 4800
  38. 2000
  39. 4000
  40. 8100

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