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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 801 · 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 243 + 705? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 97 × 60? (a) 600 (b) 60000 (c) 6000
  3. 3.Best estimate of 517 + 140? (a) 800 (b) 400 (c) 600
  4. 4.Best estimate of 18 × 60? (a) 120 (b) 12000 (c) 1200
  5. 5.Best estimate of 383 + 232? (a) 800 (b) 400 (c) 600
  6. 6.Best estimate of 80 × 48? (a) 4000 (b) 400 (c) 40000
  7. 7.Best estimate of 92 × 90? (a) 81000 (b) 8100 (c) 810
  8. 8.Best estimate of 815 + 240? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 84 × 44? (a) 3200 (b) 32000 (c) 320
  10. 10.Best estimate of 261 + 875? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 781 + 294? (a) 900 (b) 1100 (c) 1300
  12. 12.Best estimate of 580 + 299? (a) 900 (b) 700 (c) 1100
  13. 13.Best estimate of 76 × 66? (a) 5600 (b) 56000 (c) 560
  14. 14.Best estimate of 851 + 727? (a) 1400 (b) 1800 (c) 1600
  15. 15.Best estimate of 855 + 741? (a) 1400 (b) 1600 (c) 1800
  16. 16.Best estimate of 70 × 88? (a) 630 (b) 6300 (c) 63000
  17. 17.Best estimate of 163 + 659? (a) 900 (b) 1100 (c) 700
  18. 18.Best estimate of 566 + 424? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 489 + 508? (a) 1200 (b) 800 (c) 1000
  20. 20.Best estimate of 79 × 70? (a) 5600 (b) 560 (c) 56000
  21. 21.Best estimate of 26 × 90? (a) 2700 (b) 270 (c) 27000
  22. 22.Best estimate of 26 × 48? (a) 150 (b) 1500 (c) 15000
  23. 23.Best estimate of 33 × 33? (a) 9000 (b) 900 (c) 90
  24. 24.Best estimate of 381 + 781? (a) 1200 (b) 1000 (c) 1400
  25. 25.Best estimate of 59 × 86? (a) 540 (b) 54000 (c) 5400
  26. 26.Best estimate of 56 × 42? (a) 2400 (b) 24000 (c) 240
  27. 27.Best estimate of 330 + 192? (a) 500 (b) 300 (c) 700
  28. 28.Best estimate of 13 × 73? (a) 7000 (b) 700 (c) 70
  29. 29.Best estimate of 12 × 32? (a) 300 (b) 30 (c) 3000
  30. 30.Best estimate of 191 + 340? (a) 700 (b) 500 (c) 300
  31. 31.Best estimate of 302 + 646? (a) 1100 (b) 900 (c) 700
  32. 32.Best estimate of 555 + 324? (a) 700 (b) 900 (c) 1100
  33. 33.Best estimate of 576 + 799? (a) 1400 (b) 1600 (c) 1200
  34. 34.Best estimate of 343 + 167? (a) 700 (b) 300 (c) 500
  35. 35.Best estimate of 223 + 535? (a) 700 (b) 500 (c) 900
  36. 36.Best estimate of 36 × 17? (a) 80 (b) 8000 (c) 800
  37. 37.Best estimate of 194 + 521? (a) 900 (b) 500 (c) 700
  38. 38.Best estimate of 28 × 62? (a) 180 (b) 1800 (c) 18000
  39. 39.Best estimate of 54 × 40? (a) 2000 (b) 200 (c) 20000
  40. 40.Best estimate of 323 + 140? (a) 600 (b) 200 (c) 400

Answer key

  1. 900
  2. 6000
  3. 600
  4. 1200
  5. 600
  6. 4000
  7. 8100
  8. 1000
  9. 3200
  10. 1200
  11. 1100
  12. 900
  13. 5600
  14. 1600
  15. 1600
  16. 6300
  17. 900
  18. 1000
  19. 1000
  20. 5600
  21. 2700
  22. 1500
  23. 900
  24. 1200
  25. 5400
  26. 2400
  27. 500
  28. 700
  29. 300
  30. 500
  31. 900
  32. 900
  33. 1400
  34. 500
  35. 700
  36. 800
  37. 700
  38. 1800
  39. 2000
  40. 400

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