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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 490 · 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 33 × 40? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 62 × 46? (a) 3000 (b) 30000 (c) 300
  3. 3.Best estimate of 617 + 647? (a) 1400 (b) 1000 (c) 1200
  4. 4.Best estimate of 427 + 696? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 18 × 59? (a) 1200 (b) 12000 (c) 120
  6. 6.Best estimate of 132 + 325? (a) 400 (b) 200 (c) 600
  7. 7.Best estimate of 238 + 644? (a) 600 (b) 800 (c) 1000
  8. 8.Best estimate of 86 × 64? (a) 5400 (b) 540 (c) 54000
  9. 9.Best estimate of 96 × 66? (a) 70000 (b) 700 (c) 7000
  10. 10.Best estimate of 73 × 98? (a) 70000 (b) 7000 (c) 700
  11. 11.Best estimate of 76 × 39? (a) 320 (b) 3200 (c) 32000
  12. 12.Best estimate of 16 × 52? (a) 10000 (b) 100 (c) 1000
  13. 13.Best estimate of 130 + 486? (a) 800 (b) 400 (c) 600
  14. 14.Best estimate of 86 × 18? (a) 180 (b) 1800 (c) 18000
  15. 15.Best estimate of 812 + 574? (a) 1400 (b) 1600 (c) 1200
  16. 16.Best estimate of 575 + 145? (a) 900 (b) 700 (c) 500
  17. 17.Best estimate of 342 + 212? (a) 700 (b) 300 (c) 500
  18. 18.Best estimate of 64 × 90? (a) 54000 (b) 540 (c) 5400
  19. 19.Best estimate of 91 × 66? (a) 630 (b) 63000 (c) 6300
  20. 20.Best estimate of 92 × 40? (a) 3600 (b) 36000 (c) 360
  21. 21.Best estimate of 42 × 24? (a) 80 (b) 8000 (c) 800
  22. 22.Best estimate of 38 × 53? (a) 20000 (b) 200 (c) 2000
  23. 23.Best estimate of 341 + 382? (a) 700 (b) 500 (c) 900
  24. 24.Best estimate of 53 × 26? (a) 15000 (b) 1500 (c) 150
  25. 25.Best estimate of 194 + 693? (a) 900 (b) 700 (c) 1100
  26. 26.Best estimate of 89 × 12? (a) 900 (b) 90 (c) 9000
  27. 27.Best estimate of 27 × 18? (a) 600 (b) 60 (c) 6000
  28. 28.Best estimate of 22 × 19? (a) 400 (b) 40 (c) 4000
  29. 29.Best estimate of 91 × 89? (a) 8100 (b) 81000 (c) 810
  30. 30.Best estimate of 297 + 315? (a) 800 (b) 600 (c) 400
  31. 31.Best estimate of 43 × 29? (a) 120 (b) 1200 (c) 12000
  32. 32.Best estimate of 96 × 26? (a) 30000 (b) 300 (c) 3000
  33. 33.Best estimate of 245 + 623? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 126 + 278? (a) 400 (b) 200 (c) 600
  35. 35.Best estimate of 408 + 144? (a) 500 (b) 700 (c) 300
  36. 36.Best estimate of 46 × 76? (a) 4000 (b) 40000 (c) 400
  37. 37.Best estimate of 89 × 63? (a) 5400 (b) 54000 (c) 540
  38. 38.Best estimate of 149 + 853? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 59 × 61? (a) 360 (b) 36000 (c) 3600
  40. 40.Best estimate of 63 × 70? (a) 420 (b) 42000 (c) 4200

Answer key

  1. 1200
  2. 3000
  3. 1200
  4. 1100
  5. 1200
  6. 400
  7. 800
  8. 5400
  9. 7000
  10. 7000
  11. 3200
  12. 1000
  13. 600
  14. 1800
  15. 1400
  16. 700
  17. 500
  18. 5400
  19. 6300
  20. 3600
  21. 800
  22. 2000
  23. 700
  24. 1500
  25. 900
  26. 900
  27. 600
  28. 400
  29. 8100
  30. 600
  31. 1200
  32. 3000
  33. 800
  34. 400
  35. 500
  36. 4000
  37. 5400
  38. 1000
  39. 3600
  40. 4200

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