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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 965 · 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 535 + 720? (a) 1200 (b) 1400 (c) 1000
  2. 2.Best estimate of 94 × 46? (a) 4500 (b) 45000 (c) 450
  3. 3.Best estimate of 289 + 629? (a) 1100 (b) 900 (c) 700
  4. 4.Best estimate of 29 × 93? (a) 2700 (b) 27000 (c) 270
  5. 5.Best estimate of 67 × 18? (a) 14000 (b) 1400 (c) 140
  6. 6.Best estimate of 832 + 853? (a) 1900 (b) 1500 (c) 1700
  7. 7.Best estimate of 784 + 486? (a) 1300 (b) 1500 (c) 1100
  8. 8.Best estimate of 33 × 26? (a) 900 (b) 90 (c) 9000
  9. 9.Best estimate of 51 × 62? (a) 30000 (b) 3000 (c) 300
  10. 10.Best estimate of 44 × 28? (a) 12000 (b) 120 (c) 1200
  11. 11.Best estimate of 77 × 60? (a) 480 (b) 4800 (c) 48000
  12. 12.Best estimate of 53 × 80? (a) 4000 (b) 400 (c) 40000
  13. 13.Best estimate of 30 × 26? (a) 90 (b) 900 (c) 9000
  14. 14.Best estimate of 93 × 69? (a) 63000 (b) 6300 (c) 630
  15. 15.Best estimate of 79 × 78? (a) 640 (b) 6400 (c) 64000
  16. 16.Best estimate of 36 × 37? (a) 160 (b) 16000 (c) 1600
  17. 17.Best estimate of 259 + 439? (a) 700 (b) 900 (c) 500
  18. 18.Best estimate of 16 × 30? (a) 60 (b) 600 (c) 6000
  19. 19.Best estimate of 462 + 752? (a) 1500 (b) 1300 (c) 1100
  20. 20.Best estimate of 26 × 69? (a) 2100 (b) 210 (c) 21000
  21. 21.Best estimate of 68 × 16? (a) 1400 (b) 140 (c) 14000
  22. 22.Best estimate of 47 × 92? (a) 4500 (b) 450 (c) 45000
  23. 23.Best estimate of 17 × 37? (a) 80 (b) 8000 (c) 800
  24. 24.Best estimate of 851 + 220? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 221 + 358? (a) 400 (b) 800 (c) 600
  26. 26.Best estimate of 38 × 83? (a) 32000 (b) 320 (c) 3200
  27. 27.Best estimate of 277 + 627? (a) 700 (b) 1100 (c) 900
  28. 28.Best estimate of 43 × 83? (a) 3200 (b) 32000 (c) 320
  29. 29.Best estimate of 46 × 13? (a) 50 (b) 5000 (c) 500
  30. 30.Best estimate of 96 × 96? (a) 100000 (b) 10000 (c) 1000
  31. 31.Best estimate of 471 + 231? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 50 × 47? (a) 25000 (b) 250 (c) 2500
  33. 33.Best estimate of 543 + 277? (a) 600 (b) 800 (c) 1000
  34. 34.Best estimate of 82 × 33? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 86 × 47? (a) 4500 (b) 45000 (c) 450
  36. 36.Best estimate of 69 × 46? (a) 350 (b) 3500 (c) 35000
  37. 37.Best estimate of 42 × 18? (a) 800 (b) 8000 (c) 80
  38. 38.Best estimate of 38 × 60? (a) 240 (b) 24000 (c) 2400
  39. 39.Best estimate of 87 × 98? (a) 9000 (b) 900 (c) 90000
  40. 40.Best estimate of 79 × 53? (a) 400 (b) 40000 (c) 4000

Answer key

  1. 1200
  2. 4500
  3. 900
  4. 2700
  5. 1400
  6. 1700
  7. 1300
  8. 900
  9. 3000
  10. 1200
  11. 4800
  12. 4000
  13. 900
  14. 6300
  15. 6400
  16. 1600
  17. 700
  18. 600
  19. 1300
  20. 2100
  21. 1400
  22. 4500
  23. 800
  24. 1100
  25. 600
  26. 3200
  27. 900
  28. 3200
  29. 500
  30. 10000
  31. 700
  32. 2500
  33. 800
  34. 2400
  35. 4500
  36. 3500
  37. 800
  38. 2400
  39. 9000
  40. 4000

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