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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 970 · 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 23 × 64? (a) 1200 (b) 120 (c) 12000
  2. 2.Best estimate of 19 × 92? (a) 1800 (b) 180 (c) 18000
  3. 3.Best estimate of 597 + 212? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 56 × 26? (a) 1800 (b) 180 (c) 18000
  5. 5.Best estimate of 160 + 377? (a) 800 (b) 400 (c) 600
  6. 6.Best estimate of 59 × 36? (a) 24000 (b) 2400 (c) 240
  7. 7.Best estimate of 840 + 779? (a) 1800 (b) 1400 (c) 1600
  8. 8.Best estimate of 544 + 120? (a) 400 (b) 800 (c) 600
  9. 9.Best estimate of 451 + 561? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 234 + 856? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 82 × 48? (a) 4000 (b) 400 (c) 40000
  12. 12.Best estimate of 69 × 53? (a) 3500 (b) 35000 (c) 350
  13. 13.Best estimate of 16 × 87? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 722 + 125? (a) 600 (b) 1000 (c) 800
  15. 15.Best estimate of 46 × 49? (a) 25000 (b) 250 (c) 2500
  16. 16.Best estimate of 86 × 18? (a) 180 (b) 1800 (c) 18000
  17. 17.Best estimate of 33 × 68? (a) 2100 (b) 21000 (c) 210
  18. 18.Best estimate of 627 + 880? (a) 1500 (b) 1300 (c) 1700
  19. 19.Best estimate of 856 + 429? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 39 × 56? (a) 2400 (b) 24000 (c) 240
  21. 21.Best estimate of 465 + 159? (a) 900 (b) 700 (c) 500
  22. 22.Best estimate of 860 + 177? (a) 900 (b) 1100 (c) 1300
  23. 23.Best estimate of 16 × 74? (a) 1400 (b) 140 (c) 14000
  24. 24.Best estimate of 76 × 36? (a) 3200 (b) 32000 (c) 320
  25. 25.Best estimate of 531 + 305? (a) 800 (b) 600 (c) 1000
  26. 26.Best estimate of 97 × 58? (a) 600 (b) 60000 (c) 6000
  27. 27.Best estimate of 89 × 18? (a) 18000 (b) 1800 (c) 180
  28. 28.Best estimate of 451 + 571? (a) 1300 (b) 1100 (c) 900
  29. 29.Best estimate of 39 × 98? (a) 400 (b) 40000 (c) 4000
  30. 30.Best estimate of 180 + 203? (a) 200 (b) 600 (c) 400
  31. 31.Best estimate of 738 + 346? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 368 + 669? (a) 1300 (b) 1100 (c) 900
  33. 33.Best estimate of 410 + 335? (a) 700 (b) 900 (c) 500
  34. 34.Best estimate of 43 × 30? (a) 1200 (b) 12000 (c) 120
  35. 35.Best estimate of 38 × 69? (a) 2800 (b) 28000 (c) 280
  36. 36.Best estimate of 26 × 61? (a) 18000 (b) 180 (c) 1800
  37. 37.Best estimate of 147 + 751? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 53 × 19? (a) 1000 (b) 10000 (c) 100
  39. 39.Best estimate of 30 × 24? (a) 6000 (b) 60 (c) 600
  40. 40.Best estimate of 200 + 124? (a) 500 (b) 300 (c) 100

Answer key

  1. 1200
  2. 1800
  3. 800
  4. 1800
  5. 600
  6. 2400
  7. 1600
  8. 600
  9. 1100
  10. 1100
  11. 4000
  12. 3500
  13. 1800
  14. 800
  15. 2500
  16. 1800
  17. 2100
  18. 1500
  19. 1300
  20. 2400
  21. 700
  22. 1100
  23. 1400
  24. 3200
  25. 800
  26. 6000
  27. 1800
  28. 1100
  29. 4000
  30. 400
  31. 1000
  32. 1100
  33. 700
  34. 1200
  35. 2800
  36. 1800
  37. 900
  38. 1000
  39. 600
  40. 300

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