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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 56 · 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 611 + 249? (a) 600 (b) 800 (c) 1000
  2. 2.Best estimate of 77 × 53? (a) 40000 (b) 400 (c) 4000
  3. 3.Best estimate of 19 × 16? (a) 4000 (b) 40 (c) 400
  4. 4.Best estimate of 34 × 90? (a) 2700 (b) 270 (c) 27000
  5. 5.Best estimate of 56 × 86? (a) 540 (b) 5400 (c) 54000
  6. 6.Best estimate of 259 + 433? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 94 × 12? (a) 90 (b) 900 (c) 9000
  8. 8.Best estimate of 815 + 451? (a) 1300 (b) 1500 (c) 1100
  9. 9.Best estimate of 83 × 19? (a) 1600 (b) 16000 (c) 160
  10. 10.Best estimate of 143 + 441? (a) 500 (b) 700 (c) 300
  11. 11.Best estimate of 72 × 52? (a) 350 (b) 3500 (c) 35000
  12. 12.Best estimate of 702 + 484? (a) 1400 (b) 1200 (c) 1000
  13. 13.Best estimate of 380 + 811? (a) 1400 (b) 1200 (c) 1000
  14. 14.Best estimate of 790 + 617? (a) 1600 (b) 1400 (c) 1200
  15. 15.Best estimate of 652 + 305? (a) 800 (b) 1200 (c) 1000
  16. 16.Best estimate of 194 + 170? (a) 400 (b) 600 (c) 200
  17. 17.Best estimate of 347 + 513? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 49 × 59? (a) 300 (b) 30000 (c) 3000
  19. 19.Best estimate of 82 × 39? (a) 32000 (b) 320 (c) 3200
  20. 20.Best estimate of 50 × 52? (a) 25000 (b) 250 (c) 2500
  21. 21.Best estimate of 219 + 877? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 63 × 13? (a) 60 (b) 6000 (c) 600
  23. 23.Best estimate of 62 × 21? (a) 120 (b) 12000 (c) 1200
  24. 24.Best estimate of 83 × 44? (a) 320 (b) 3200 (c) 32000
  25. 25.Best estimate of 50 × 66? (a) 350 (b) 3500 (c) 35000
  26. 26.Best estimate of 98 × 33? (a) 300 (b) 30000 (c) 3000
  27. 27.Best estimate of 601 + 291? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 16 × 70? (a) 14000 (b) 1400 (c) 140
  29. 29.Best estimate of 46 × 26? (a) 150 (b) 15000 (c) 1500
  30. 30.Best estimate of 249 + 264? (a) 300 (b) 500 (c) 700
  31. 31.Best estimate of 551 + 811? (a) 1400 (b) 1600 (c) 1200
  32. 32.Best estimate of 256 + 239? (a) 300 (b) 500 (c) 700
  33. 33.Best estimate of 61 × 80? (a) 480 (b) 4800 (c) 48000
  34. 34.Best estimate of 192 + 422? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 57 × 40? (a) 2400 (b) 240 (c) 24000
  36. 36.Best estimate of 93 × 83? (a) 72000 (b) 7200 (c) 720
  37. 37.Best estimate of 61 × 97? (a) 6000 (b) 60000 (c) 600
  38. 38.Best estimate of 48 × 30? (a) 1500 (b) 150 (c) 15000
  39. 39.Best estimate of 78 × 54? (a) 400 (b) 40000 (c) 4000
  40. 40.Best estimate of 751 + 826? (a) 1600 (b) 1400 (c) 1800

Answer key

  1. 800
  2. 4000
  3. 400
  4. 2700
  5. 5400
  6. 700
  7. 900
  8. 1300
  9. 1600
  10. 500
  11. 3500
  12. 1200
  13. 1200
  14. 1400
  15. 1000
  16. 400
  17. 800
  18. 3000
  19. 3200
  20. 2500
  21. 1100
  22. 600
  23. 1200
  24. 3200
  25. 3500
  26. 3000
  27. 900
  28. 1400
  29. 1500
  30. 500
  31. 1400
  32. 500
  33. 4800
  34. 600
  35. 2400
  36. 7200
  37. 6000
  38. 1500
  39. 4000
  40. 1600

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