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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 215 · 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 19 × 30? (a) 6000 (b) 60 (c) 600
  2. 2.Best estimate of 56 × 80? (a) 4800 (b) 480 (c) 48000
  3. 3.Best estimate of 77 × 36? (a) 3200 (b) 320 (c) 32000
  4. 4.Best estimate of 640 + 499? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 306 + 806? (a) 1300 (b) 900 (c) 1100
  6. 6.Best estimate of 17 × 96? (a) 2000 (b) 200 (c) 20000
  7. 7.Best estimate of 321 + 516? (a) 1000 (b) 600 (c) 800
  8. 8.Best estimate of 255 + 216? (a) 500 (b) 700 (c) 300
  9. 9.Best estimate of 68 × 46? (a) 3500 (b) 350 (c) 35000
  10. 10.Best estimate of 584 + 431? (a) 800 (b) 1000 (c) 1200
  11. 11.Best estimate of 201 + 215? (a) 200 (b) 600 (c) 400
  12. 12.Best estimate of 354 + 802? (a) 1200 (b) 1400 (c) 1000
  13. 13.Best estimate of 18 × 39? (a) 800 (b) 80 (c) 8000
  14. 14.Best estimate of 763 + 769? (a) 1400 (b) 1800 (c) 1600
  15. 15.Best estimate of 476 + 478? (a) 800 (b) 1200 (c) 1000
  16. 16.Best estimate of 98 × 96? (a) 10000 (b) 100000 (c) 1000
  17. 17.Best estimate of 227 + 782? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 296 + 430? (a) 500 (b) 700 (c) 900
  19. 19.Best estimate of 81 × 33? (a) 240 (b) 2400 (c) 24000
  20. 20.Best estimate of 24 × 44? (a) 800 (b) 80 (c) 8000
  21. 21.Best estimate of 594 + 880? (a) 1700 (b) 1300 (c) 1500
  22. 22.Best estimate of 419 + 177? (a) 800 (b) 400 (c) 600
  23. 23.Best estimate of 525 + 300? (a) 1000 (b) 800 (c) 600
  24. 24.Best estimate of 292 + 129? (a) 400 (b) 600 (c) 200
  25. 25.Best estimate of 39 × 76? (a) 3200 (b) 32000 (c) 320
  26. 26.Best estimate of 42 × 16? (a) 80 (b) 8000 (c) 800
  27. 27.Best estimate of 315 + 731? (a) 800 (b) 1200 (c) 1000
  28. 28.Best estimate of 46 × 14? (a) 5000 (b) 50 (c) 500
  29. 29.Best estimate of 32 × 74? (a) 21000 (b) 210 (c) 2100
  30. 30.Best estimate of 36 × 16? (a) 8000 (b) 80 (c) 800
  31. 31.Best estimate of 61 × 70? (a) 4200 (b) 420 (c) 42000
  32. 32.Best estimate of 298 + 429? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 670 + 211? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 19 × 76? (a) 160 (b) 1600 (c) 16000
  35. 35.Best estimate of 97 × 51? (a) 500 (b) 5000 (c) 50000
  36. 36.Best estimate of 20 × 48? (a) 1000 (b) 100 (c) 10000
  37. 37.Best estimate of 89 × 50? (a) 450 (b) 45000 (c) 4500
  38. 38.Best estimate of 74 × 51? (a) 3500 (b) 35000 (c) 350
  39. 39.Best estimate of 834 + 349? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 61 × 98? (a) 6000 (b) 600 (c) 60000

Answer key

  1. 600
  2. 4800
  3. 3200
  4. 1100
  5. 1100
  6. 2000
  7. 800
  8. 500
  9. 3500
  10. 1000
  11. 400
  12. 1200
  13. 800
  14. 1600
  15. 1000
  16. 10000
  17. 1000
  18. 700
  19. 2400
  20. 800
  21. 1500
  22. 600
  23. 800
  24. 400
  25. 3200
  26. 800
  27. 1000
  28. 500
  29. 2100
  30. 800
  31. 4200
  32. 700
  33. 900
  34. 1600
  35. 5000
  36. 1000
  37. 4500
  38. 3500
  39. 1100
  40. 6000

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