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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 791 · 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 401 + 143? (a) 700 (b) 300 (c) 500
  2. 2.Best estimate of 252 + 380? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 265 + 851? (a) 1000 (b) 1200 (c) 1400
  4. 4.Best estimate of 91 × 30? (a) 27000 (b) 270 (c) 2700
  5. 5.Best estimate of 16 × 48? (a) 100 (b) 10000 (c) 1000
  6. 6.Best estimate of 88 × 93? (a) 8100 (b) 81000 (c) 810
  7. 7.Best estimate of 14 × 76? (a) 800 (b) 8000 (c) 80
  8. 8.Best estimate of 33 × 53? (a) 150 (b) 15000 (c) 1500
  9. 9.Best estimate of 28 × 31? (a) 9000 (b) 90 (c) 900
  10. 10.Best estimate of 83 × 42? (a) 320 (b) 3200 (c) 32000
  11. 11.Best estimate of 647 + 713? (a) 1100 (b) 1300 (c) 1500
  12. 12.Best estimate of 630 + 228? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 86 × 34? (a) 2700 (b) 270 (c) 27000
  14. 14.Best estimate of 56 × 30? (a) 18000 (b) 180 (c) 1800
  15. 15.Best estimate of 652 + 542? (a) 1400 (b) 1200 (c) 1000
  16. 16.Best estimate of 686 + 269? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 786 + 728? (a) 1300 (b) 1700 (c) 1500
  18. 18.Best estimate of 71 × 57? (a) 42000 (b) 420 (c) 4200
  19. 19.Best estimate of 342 + 341? (a) 600 (b) 400 (c) 800
  20. 20.Best estimate of 294 + 169? (a) 500 (b) 300 (c) 700
  21. 21.Best estimate of 67 × 12? (a) 7000 (b) 70 (c) 700
  22. 22.Best estimate of 202 + 187? (a) 600 (b) 400 (c) 200
  23. 23.Best estimate of 225 + 407? (a) 400 (b) 600 (c) 800
  24. 24.Best estimate of 13 × 70? (a) 7000 (b) 70 (c) 700
  25. 25.Best estimate of 70 × 26? (a) 2100 (b) 210 (c) 21000
  26. 26.Best estimate of 62 × 22? (a) 120 (b) 12000 (c) 1200
  27. 27.Best estimate of 825 + 678? (a) 1700 (b) 1300 (c) 1500
  28. 28.Best estimate of 807 + 658? (a) 1300 (b) 1500 (c) 1700
  29. 29.Best estimate of 22 × 92? (a) 18000 (b) 1800 (c) 180
  30. 30.Best estimate of 440 + 639? (a) 1000 (b) 800 (c) 1200
  31. 31.Best estimate of 98 × 43? (a) 40000 (b) 4000 (c) 400
  32. 32.Best estimate of 48 × 40? (a) 200 (b) 2000 (c) 20000
  33. 33.Best estimate of 463 + 257? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 22 × 73? (a) 14000 (b) 140 (c) 1400
  35. 35.Best estimate of 26 × 56? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 180 + 878? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 26 × 32? (a) 9000 (b) 90 (c) 900
  38. 38.Best estimate of 53 × 87? (a) 4500 (b) 450 (c) 45000
  39. 39.Best estimate of 383 + 687? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 73 × 23? (a) 1400 (b) 14000 (c) 140

Answer key

  1. 500
  2. 700
  3. 1200
  4. 2700
  5. 1000
  6. 8100
  7. 800
  8. 1500
  9. 900
  10. 3200
  11. 1300
  12. 800
  13. 2700
  14. 1800
  15. 1200
  16. 1000
  17. 1500
  18. 4200
  19. 600
  20. 500
  21. 700
  22. 400
  23. 600
  24. 700
  25. 2100
  26. 1200
  27. 1500
  28. 1500
  29. 1800
  30. 1000
  31. 4000
  32. 2000
  33. 800
  34. 1400
  35. 1800
  36. 1100
  37. 900
  38. 4500
  39. 1100
  40. 1400

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