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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 487 · 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 341 + 267? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 773 + 282? (a) 1300 (b) 1100 (c) 900
  3. 3.Best estimate of 33 × 47? (a) 15000 (b) 150 (c) 1500
  4. 4.Best estimate of 699 + 713? (a) 1600 (b) 1400 (c) 1200
  5. 5.Best estimate of 420 + 327? (a) 700 (b) 900 (c) 500
  6. 6.Best estimate of 73 × 30? (a) 210 (b) 21000 (c) 2100
  7. 7.Best estimate of 733 + 181? (a) 700 (b) 1100 (c) 900
  8. 8.Best estimate of 19 × 43? (a) 800 (b) 80 (c) 8000
  9. 9.Best estimate of 36 × 53? (a) 200 (b) 2000 (c) 20000
  10. 10.Best estimate of 626 + 758? (a) 1200 (b) 1600 (c) 1400
  11. 11.Best estimate of 490 + 684? (a) 1200 (b) 1400 (c) 1000
  12. 12.Best estimate of 43 × 58? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 20 × 47? (a) 10000 (b) 100 (c) 1000
  14. 14.Best estimate of 294 + 127? (a) 600 (b) 200 (c) 400
  15. 15.Best estimate of 825 + 713? (a) 1700 (b) 1500 (c) 1300
  16. 16.Best estimate of 706 + 420? (a) 900 (b) 1300 (c) 1100
  17. 17.Best estimate of 407 + 639? (a) 1200 (b) 1000 (c) 800
  18. 18.Best estimate of 96 × 50? (a) 5000 (b) 500 (c) 50000
  19. 19.Best estimate of 39 × 78? (a) 3200 (b) 320 (c) 32000
  20. 20.Best estimate of 63 × 77? (a) 48000 (b) 4800 (c) 480
  21. 21.Best estimate of 853 + 320? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 468 + 271? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 26 × 64? (a) 1800 (b) 180 (c) 18000
  24. 24.Best estimate of 138 + 625? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 30 × 19? (a) 6000 (b) 600 (c) 60
  26. 26.Best estimate of 180 + 443? (a) 600 (b) 800 (c) 400
  27. 27.Best estimate of 848 + 226? (a) 1200 (b) 1000 (c) 800
  28. 28.Best estimate of 434 + 392? (a) 800 (b) 1000 (c) 600
  29. 29.Best estimate of 639 + 180? (a) 800 (b) 1000 (c) 600
  30. 30.Best estimate of 81 × 49? (a) 40000 (b) 400 (c) 4000
  31. 31.Best estimate of 761 + 188? (a) 1200 (b) 1000 (c) 800
  32. 32.Best estimate of 24 × 22? (a) 4000 (b) 40 (c) 400
  33. 33.Best estimate of 247 + 506? (a) 900 (b) 500 (c) 700
  34. 34.Best estimate of 863 + 162? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 214 + 390? (a) 800 (b) 600 (c) 400
  36. 36.Best estimate of 34 × 31? (a) 9000 (b) 900 (c) 90
  37. 37.Best estimate of 538 + 624? (a) 900 (b) 1100 (c) 1300
  38. 38.Best estimate of 306 + 213? (a) 500 (b) 300 (c) 700
  39. 39.Best estimate of 51 × 37? (a) 20000 (b) 2000 (c) 200
  40. 40.Best estimate of 98 × 72? (a) 70000 (b) 7000 (c) 700

Answer key

  1. 600
  2. 1100
  3. 1500
  4. 1400
  5. 700
  6. 2100
  7. 900
  8. 800
  9. 2000
  10. 1400
  11. 1200
  12. 2400
  13. 1000
  14. 400
  15. 1500
  16. 1100
  17. 1000
  18. 5000
  19. 3200
  20. 4800
  21. 1200
  22. 800
  23. 1800
  24. 700
  25. 600
  26. 600
  27. 1000
  28. 800
  29. 800
  30. 4000
  31. 1000
  32. 400
  33. 700
  34. 1100
  35. 600
  36. 900
  37. 1100
  38. 500
  39. 2000
  40. 7000

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