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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 890 · 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 680 + 835? (a) 1500 (b) 1300 (c) 1700
  2. 2.Best estimate of 41 × 77? (a) 3200 (b) 320 (c) 32000
  3. 3.Best estimate of 738 + 252? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 56 × 41? (a) 240 (b) 24000 (c) 2400
  5. 5.Best estimate of 584 + 525? (a) 900 (b) 1300 (c) 1100
  6. 6.Best estimate of 619 + 737? (a) 1500 (b) 1100 (c) 1300
  7. 7.Best estimate of 707 + 218? (a) 900 (b) 700 (c) 1100
  8. 8.Best estimate of 40 × 70? (a) 2800 (b) 28000 (c) 280
  9. 9.Best estimate of 485 + 774? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 125 + 785? (a) 700 (b) 1100 (c) 900
  11. 11.Best estimate of 305 + 839? (a) 1300 (b) 900 (c) 1100
  12. 12.Best estimate of 839 + 838? (a) 1400 (b) 1800 (c) 1600
  13. 13.Best estimate of 16 × 29? (a) 600 (b) 60 (c) 6000
  14. 14.Best estimate of 867 + 561? (a) 1700 (b) 1500 (c) 1300
  15. 15.Best estimate of 77 × 76? (a) 6400 (b) 640 (c) 64000
  16. 16.Best estimate of 734 + 399? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 817 + 538? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 30 × 31? (a) 900 (b) 9000 (c) 90
  19. 19.Best estimate of 509 + 828? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 722 + 200? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 47 × 96? (a) 5000 (b) 50000 (c) 500
  22. 22.Best estimate of 64 × 33? (a) 18000 (b) 180 (c) 1800
  23. 23.Best estimate of 374 + 840? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 872 + 718? (a) 1800 (b) 1600 (c) 1400
  25. 25.Best estimate of 386 + 626? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 86 × 72? (a) 6300 (b) 630 (c) 63000
  27. 27.Best estimate of 56 × 56? (a) 360 (b) 36000 (c) 3600
  28. 28.Best estimate of 679 + 194? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 21 × 86? (a) 1800 (b) 180 (c) 18000
  30. 30.Best estimate of 66 × 13? (a) 700 (b) 7000 (c) 70
  31. 31.Best estimate of 24 × 36? (a) 800 (b) 80 (c) 8000
  32. 32.Best estimate of 61 × 71? (a) 4200 (b) 42000 (c) 420
  33. 33.Best estimate of 382 + 645? (a) 1200 (b) 800 (c) 1000
  34. 34.Best estimate of 44 × 80? (a) 32000 (b) 3200 (c) 320
  35. 35.Best estimate of 26 × 86? (a) 27000 (b) 270 (c) 2700
  36. 36.Best estimate of 546 + 442? (a) 1100 (b) 700 (c) 900
  37. 37.Best estimate of 68 × 16? (a) 1400 (b) 14000 (c) 140
  38. 38.Best estimate of 821 + 148? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 34 × 13? (a) 300 (b) 30 (c) 3000
  40. 40.Best estimate of 91 × 26? (a) 2700 (b) 27000 (c) 270

Answer key

  1. 1500
  2. 3200
  3. 1000
  4. 2400
  5. 1100
  6. 1300
  7. 900
  8. 2800
  9. 1300
  10. 900
  11. 1100
  12. 1600
  13. 600
  14. 1500
  15. 6400
  16. 1100
  17. 1300
  18. 900
  19. 1300
  20. 900
  21. 5000
  22. 1800
  23. 1200
  24. 1600
  25. 1000
  26. 6300
  27. 3600
  28. 900
  29. 1800
  30. 700
  31. 800
  32. 4200
  33. 1000
  34. 3200
  35. 2700
  36. 900
  37. 1400
  38. 900
  39. 300
  40. 2700

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