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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 87 · 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 + 775? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 12 × 71? (a) 700 (b) 70 (c) 7000
  3. 3.Best estimate of 159 + 200? (a) 200 (b) 600 (c) 400
  4. 4.Best estimate of 619 + 738? (a) 1100 (b) 1500 (c) 1300
  5. 5.Best estimate of 91 × 53? (a) 450 (b) 45000 (c) 4500
  6. 6.Best estimate of 123 + 364? (a) 300 (b) 700 (c) 500
  7. 7.Best estimate of 29 × 92? (a) 270 (b) 2700 (c) 27000
  8. 8.Best estimate of 488 + 775? (a) 1100 (b) 1500 (c) 1300
  9. 9.Best estimate of 577 + 300? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 46 × 59? (a) 3000 (b) 30000 (c) 300
  11. 11.Best estimate of 360 + 239? (a) 400 (b) 800 (c) 600
  12. 12.Best estimate of 451 + 823? (a) 1300 (b) 1100 (c) 1500
  13. 13.Best estimate of 538 + 219? (a) 700 (b) 900 (c) 500
  14. 14.Best estimate of 186 + 432? (a) 800 (b) 600 (c) 400
  15. 15.Best estimate of 578 + 614? (a) 1200 (b) 1400 (c) 1000
  16. 16.Best estimate of 24 × 96? (a) 2000 (b) 200 (c) 20000
  17. 17.Best estimate of 38 × 59? (a) 2400 (b) 240 (c) 24000
  18. 18.Best estimate of 84 × 43? (a) 32000 (b) 3200 (c) 320
  19. 19.Best estimate of 485 + 486? (a) 1200 (b) 800 (c) 1000
  20. 20.Best estimate of 771 + 148? (a) 900 (b) 1100 (c) 700
  21. 21.Best estimate of 453 + 671? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 277 + 716? (a) 800 (b) 1000 (c) 1200
  23. 23.Best estimate of 91 × 52? (a) 4500 (b) 450 (c) 45000
  24. 24.Best estimate of 487 + 740? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 726 + 468? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 605 + 675? (a) 1500 (b) 1100 (c) 1300
  27. 27.Best estimate of 53 × 70? (a) 35000 (b) 3500 (c) 350
  28. 28.Best estimate of 544 + 874? (a) 1600 (b) 1200 (c) 1400
  29. 29.Best estimate of 386 + 743? (a) 900 (b) 1100 (c) 1300
  30. 30.Best estimate of 27 × 36? (a) 120 (b) 12000 (c) 1200
  31. 31.Best estimate of 12 × 36? (a) 4000 (b) 400 (c) 40
  32. 32.Best estimate of 50 × 16? (a) 10000 (b) 100 (c) 1000
  33. 33.Best estimate of 33 × 77? (a) 24000 (b) 240 (c) 2400
  34. 34.Best estimate of 376 + 444? (a) 1000 (b) 600 (c) 800
  35. 35.Best estimate of 39 × 38? (a) 1600 (b) 16000 (c) 160
  36. 36.Best estimate of 225 + 137? (a) 300 (b) 500 (c) 100
  37. 37.Best estimate of 19 × 12? (a) 20 (b) 2000 (c) 200
  38. 38.Best estimate of 874 + 710? (a) 1800 (b) 1600 (c) 1400
  39. 39.Best estimate of 50 × 50? (a) 250 (b) 25000 (c) 2500
  40. 40.Best estimate of 96 × 29? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 1000
  2. 700
  3. 400
  4. 1300
  5. 4500
  6. 500
  7. 2700
  8. 1300
  9. 900
  10. 3000
  11. 600
  12. 1300
  13. 700
  14. 600
  15. 1200
  16. 2000
  17. 2400
  18. 3200
  19. 1000
  20. 900
  21. 1200
  22. 1000
  23. 4500
  24. 1200
  25. 1200
  26. 1300
  27. 3500
  28. 1400
  29. 1100
  30. 1200
  31. 400
  32. 1000
  33. 2400
  34. 800
  35. 1600
  36. 300
  37. 200
  38. 1600
  39. 2500
  40. 3000

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