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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 6 · 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 271 + 766? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 36 × 46? (a) 2000 (b) 200 (c) 20000
  3. 3.Best estimate of 351 + 170? (a) 800 (b) 600 (c) 400
  4. 4.Best estimate of 839 + 482? (a) 1100 (b) 1500 (c) 1300
  5. 5.Best estimate of 83 × 36? (a) 3200 (b) 320 (c) 32000
  6. 6.Best estimate of 79 × 18? (a) 160 (b) 1600 (c) 16000
  7. 7.Best estimate of 40 × 30? (a) 1200 (b) 12000 (c) 120
  8. 8.Best estimate of 439 + 287? (a) 500 (b) 900 (c) 700
  9. 9.Best estimate of 88 × 30? (a) 2700 (b) 270 (c) 27000
  10. 10.Best estimate of 772 + 723? (a) 1500 (b) 1300 (c) 1700
  11. 11.Best estimate of 64 × 53? (a) 30000 (b) 3000 (c) 300
  12. 12.Best estimate of 179 + 666? (a) 700 (b) 1100 (c) 900
  13. 13.Best estimate of 59 × 53? (a) 300 (b) 30000 (c) 3000
  14. 14.Best estimate of 69 × 24? (a) 14000 (b) 140 (c) 1400
  15. 15.Best estimate of 41 × 16? (a) 80 (b) 8000 (c) 800
  16. 16.Best estimate of 240 + 873? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 36 × 17? (a) 80 (b) 800 (c) 8000
  18. 18.Best estimate of 31 × 34? (a) 90 (b) 900 (c) 9000
  19. 19.Best estimate of 71 × 31? (a) 210 (b) 21000 (c) 2100
  20. 20.Best estimate of 399 + 622? (a) 800 (b) 1000 (c) 1200
  21. 21.Best estimate of 209 + 855? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 53 × 96? (a) 5000 (b) 50000 (c) 500
  23. 23.Best estimate of 89 × 26? (a) 2700 (b) 27000 (c) 270
  24. 24.Best estimate of 43 × 14? (a) 400 (b) 40 (c) 4000
  25. 25.Best estimate of 96 × 47? (a) 5000 (b) 500 (c) 50000
  26. 26.Best estimate of 646 + 786? (a) 1400 (b) 1200 (c) 1600
  27. 27.Best estimate of 66 × 79? (a) 5600 (b) 56000 (c) 560
  28. 28.Best estimate of 66 × 18? (a) 1400 (b) 140 (c) 14000
  29. 29.Best estimate of 308 + 759? (a) 1100 (b) 1300 (c) 900
  30. 30.Best estimate of 295 + 842? (a) 900 (b) 1100 (c) 1300
  31. 31.Best estimate of 20 × 90? (a) 18000 (b) 180 (c) 1800
  32. 32.Best estimate of 34 × 37? (a) 12000 (b) 120 (c) 1200
  33. 33.Best estimate of 788 + 667? (a) 1300 (b) 1500 (c) 1700
  34. 34.Best estimate of 23 × 98? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 292 + 578? (a) 700 (b) 1100 (c) 900
  36. 36.Best estimate of 158 + 278? (a) 300 (b) 700 (c) 500
  37. 37.Best estimate of 177 + 551? (a) 800 (b) 600 (c) 1000
  38. 38.Best estimate of 21 × 21? (a) 4000 (b) 400 (c) 40
  39. 39.Best estimate of 44 × 43? (a) 1600 (b) 160 (c) 16000
  40. 40.Best estimate of 22 × 31? (a) 600 (b) 60 (c) 6000

Answer key

  1. 1100
  2. 2000
  3. 600
  4. 1300
  5. 3200
  6. 1600
  7. 1200
  8. 700
  9. 2700
  10. 1500
  11. 3000
  12. 900
  13. 3000
  14. 1400
  15. 800
  16. 1100
  17. 800
  18. 900
  19. 2100
  20. 1000
  21. 1100
  22. 5000
  23. 2700
  24. 400
  25. 5000
  26. 1400
  27. 5600
  28. 1400
  29. 1100
  30. 1100
  31. 1800
  32. 1200
  33. 1500
  34. 2000
  35. 900
  36. 500
  37. 800
  38. 400
  39. 1600
  40. 600

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