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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 191 · 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 39 × 54? (a) 200 (b) 2000 (c) 20000
  2. 2.Best estimate of 532 + 298? (a) 600 (b) 1000 (c) 800
  3. 3.Best estimate of 708 + 295? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 21 × 79? (a) 1600 (b) 160 (c) 16000
  5. 5.Best estimate of 152 + 804? (a) 1200 (b) 800 (c) 1000
  6. 6.Best estimate of 46 × 86? (a) 45000 (b) 4500 (c) 450
  7. 7.Best estimate of 124 + 178? (a) 300 (b) 500 (c) 100
  8. 8.Best estimate of 646 + 528? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 379 + 807? (a) 1400 (b) 1200 (c) 1000
  10. 10.Best estimate of 628 + 269? (a) 900 (b) 700 (c) 1100
  11. 11.Best estimate of 184 + 490? (a) 900 (b) 500 (c) 700
  12. 12.Best estimate of 56 × 60? (a) 36000 (b) 3600 (c) 360
  13. 13.Best estimate of 66 × 16? (a) 1400 (b) 140 (c) 14000
  14. 14.Best estimate of 49 × 51? (a) 2500 (b) 250 (c) 25000
  15. 15.Best estimate of 13 × 82? (a) 8000 (b) 800 (c) 80
  16. 16.Best estimate of 264 + 135? (a) 600 (b) 400 (c) 200
  17. 17.Best estimate of 806 + 754? (a) 1400 (b) 1800 (c) 1600
  18. 18.Best estimate of 207 + 341? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 24 × 52? (a) 10000 (b) 100 (c) 1000
  20. 20.Best estimate of 34 × 72? (a) 210 (b) 21000 (c) 2100
  21. 21.Best estimate of 849 + 305? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 172 + 329? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 20 × 52? (a) 100 (b) 10000 (c) 1000
  24. 24.Best estimate of 80 × 97? (a) 8000 (b) 800 (c) 80000
  25. 25.Best estimate of 94 × 33? (a) 2700 (b) 27000 (c) 270
  26. 26.Best estimate of 86 × 34? (a) 2700 (b) 270 (c) 27000
  27. 27.Best estimate of 227 + 574? (a) 1000 (b) 800 (c) 600
  28. 28.Best estimate of 609 + 622? (a) 1400 (b) 1200 (c) 1000
  29. 29.Best estimate of 494 + 564? (a) 1100 (b) 900 (c) 1300
  30. 30.Best estimate of 51 × 20? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 17 × 91? (a) 1800 (b) 180 (c) 18000
  32. 32.Best estimate of 88 × 27? (a) 27000 (b) 270 (c) 2700
  33. 33.Best estimate of 21 × 72? (a) 14000 (b) 1400 (c) 140
  34. 34.Best estimate of 186 + 482? (a) 500 (b) 900 (c) 700
  35. 35.Best estimate of 433 + 699? (a) 900 (b) 1100 (c) 1300
  36. 36.Best estimate of 132 + 671? (a) 1000 (b) 600 (c) 800
  37. 37.Best estimate of 91 × 90? (a) 8100 (b) 81000 (c) 810
  38. 38.Best estimate of 53 × 97? (a) 5000 (b) 50000 (c) 500
  39. 39.Best estimate of 68 × 84? (a) 56000 (b) 5600 (c) 560
  40. 40.Best estimate of 49 × 14? (a) 500 (b) 5000 (c) 50

Answer key

  1. 2000
  2. 800
  3. 1000
  4. 1600
  5. 1000
  6. 4500
  7. 300
  8. 1100
  9. 1200
  10. 900
  11. 700
  12. 3600
  13. 1400
  14. 2500
  15. 800
  16. 400
  17. 1600
  18. 500
  19. 1000
  20. 2100
  21. 1100
  22. 500
  23. 1000
  24. 8000
  25. 2700
  26. 2700
  27. 800
  28. 1200
  29. 1100
  30. 1000
  31. 1800
  32. 2700
  33. 1400
  34. 700
  35. 1100
  36. 800
  37. 8100
  38. 5000
  39. 5600
  40. 500

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