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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 265 · 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 488 + 481? (a) 800 (b) 1200 (c) 1000
  2. 2.Best estimate of 71 × 74? (a) 49000 (b) 4900 (c) 490
  3. 3.Best estimate of 27 × 12? (a) 300 (b) 30 (c) 3000
  4. 4.Best estimate of 254 + 408? (a) 900 (b) 700 (c) 500
  5. 5.Best estimate of 44 × 19? (a) 8000 (b) 800 (c) 80
  6. 6.Best estimate of 26 × 73? (a) 210 (b) 21000 (c) 2100
  7. 7.Best estimate of 678 + 216? (a) 1100 (b) 700 (c) 900
  8. 8.Best estimate of 63 × 86? (a) 540 (b) 5400 (c) 54000
  9. 9.Best estimate of 635 + 537? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 33 × 90? (a) 27000 (b) 2700 (c) 270
  11. 11.Best estimate of 66 × 71? (a) 49000 (b) 4900 (c) 490
  12. 12.Best estimate of 604 + 379? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 33 × 58? (a) 18000 (b) 180 (c) 1800
  14. 14.Best estimate of 22 × 43? (a) 8000 (b) 80 (c) 800
  15. 15.Best estimate of 28 × 30? (a) 90 (b) 900 (c) 9000
  16. 16.Best estimate of 148 + 743? (a) 800 (b) 1000 (c) 600
  17. 17.Best estimate of 299 + 251? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 12 × 46? (a) 500 (b) 50 (c) 5000
  19. 19.Best estimate of 800 + 731? (a) 1500 (b) 1300 (c) 1700
  20. 20.Best estimate of 16 × 77? (a) 1600 (b) 16000 (c) 160
  21. 21.Best estimate of 28 × 58? (a) 18000 (b) 180 (c) 1800
  22. 22.Best estimate of 16 × 42? (a) 8000 (b) 800 (c) 80
  23. 23.Best estimate of 776 + 321? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 764 + 215? (a) 800 (b) 1000 (c) 1200
  25. 25.Best estimate of 557 + 752? (a) 1400 (b) 1200 (c) 1600
  26. 26.Best estimate of 532 + 790? (a) 1100 (b) 1300 (c) 1500
  27. 27.Best estimate of 308 + 308? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 72 × 50? (a) 350 (b) 3500 (c) 35000
  29. 29.Best estimate of 521 + 338? (a) 1000 (b) 800 (c) 600
  30. 30.Best estimate of 124 + 262? (a) 200 (b) 600 (c) 400
  31. 31.Best estimate of 453 + 441? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 734 + 527? (a) 1400 (b) 1200 (c) 1000
  33. 33.Best estimate of 80 × 47? (a) 400 (b) 40000 (c) 4000
  34. 34.Best estimate of 16 × 24? (a) 40 (b) 400 (c) 4000
  35. 35.Best estimate of 382 + 565? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 17 × 30? (a) 6000 (b) 600 (c) 60
  37. 37.Best estimate of 311 + 769? (a) 1300 (b) 1100 (c) 900
  38. 38.Best estimate of 290 + 366? (a) 700 (b) 900 (c) 500
  39. 39.Best estimate of 255 + 213? (a) 300 (b) 500 (c) 700
  40. 40.Best estimate of 78 × 29? (a) 2400 (b) 240 (c) 24000

Answer key

  1. 1000
  2. 4900
  3. 300
  4. 700
  5. 800
  6. 2100
  7. 900
  8. 5400
  9. 1100
  10. 2700
  11. 4900
  12. 1000
  13. 1800
  14. 800
  15. 900
  16. 800
  17. 600
  18. 500
  19. 1500
  20. 1600
  21. 1800
  22. 800
  23. 1100
  24. 1000
  25. 1400
  26. 1300
  27. 600
  28. 3500
  29. 800
  30. 400
  31. 900
  32. 1200
  33. 4000
  34. 400
  35. 1000
  36. 600
  37. 1100
  38. 700
  39. 500
  40. 2400

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