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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 291 · 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 694 + 544? (a) 1000 (b) 1200 (c) 1400
  2. 2.Best estimate of 628 + 674? (a) 1300 (b) 1500 (c) 1100
  3. 3.Best estimate of 52 × 23? (a) 1000 (b) 100 (c) 10000
  4. 4.Best estimate of 451 + 695? (a) 1400 (b) 1200 (c) 1000
  5. 5.Best estimate of 411 + 272? (a) 700 (b) 500 (c) 900
  6. 6.Best estimate of 90 × 72? (a) 6300 (b) 630 (c) 63000
  7. 7.Best estimate of 90 × 90? (a) 8100 (b) 810 (c) 81000
  8. 8.Best estimate of 389 + 377? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 46 × 51? (a) 250 (b) 25000 (c) 2500
  10. 10.Best estimate of 58 × 58? (a) 36000 (b) 3600 (c) 360
  11. 11.Best estimate of 405 + 275? (a) 500 (b) 900 (c) 700
  12. 12.Best estimate of 568 + 246? (a) 800 (b) 1000 (c) 600
  13. 13.Best estimate of 43 × 82? (a) 3200 (b) 320 (c) 32000
  14. 14.Best estimate of 189 + 851? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 83 × 78? (a) 64000 (b) 640 (c) 6400
  16. 16.Best estimate of 96 × 67? (a) 70000 (b) 700 (c) 7000
  17. 17.Best estimate of 76 × 39? (a) 32000 (b) 3200 (c) 320
  18. 18.Best estimate of 394 + 631? (a) 1200 (b) 800 (c) 1000
  19. 19.Best estimate of 26 × 89? (a) 2700 (b) 27000 (c) 270
  20. 20.Best estimate of 228 + 609? (a) 800 (b) 600 (c) 1000
  21. 21.Best estimate of 27 × 47? (a) 1500 (b) 15000 (c) 150
  22. 22.Best estimate of 16 × 20? (a) 400 (b) 4000 (c) 40
  23. 23.Best estimate of 445 + 218? (a) 400 (b) 800 (c) 600
  24. 24.Best estimate of 36 × 77? (a) 32000 (b) 3200 (c) 320
  25. 25.Best estimate of 16 × 54? (a) 1000 (b) 100 (c) 10000
  26. 26.Best estimate of 872 + 445? (a) 1500 (b) 1100 (c) 1300
  27. 27.Best estimate of 23 × 14? (a) 2000 (b) 200 (c) 20
  28. 28.Best estimate of 587 + 512? (a) 1300 (b) 1100 (c) 900
  29. 29.Best estimate of 86 × 37? (a) 36000 (b) 3600 (c) 360
  30. 30.Best estimate of 622 + 155? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 16 × 16? (a) 40 (b) 4000 (c) 400
  32. 32.Best estimate of 734 + 248? (a) 1100 (b) 900 (c) 700
  33. 33.Best estimate of 346 + 148? (a) 600 (b) 400 (c) 200
  34. 34.Best estimate of 786 + 335? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 263 + 310? (a) 800 (b) 400 (c) 600
  36. 36.Best estimate of 18 × 62? (a) 120 (b) 12000 (c) 1200
  37. 37.Best estimate of 72 × 36? (a) 2800 (b) 280 (c) 28000
  38. 38.Best estimate of 151 + 837? (a) 1000 (b) 800 (c) 1200
  39. 39.Best estimate of 606 + 771? (a) 1600 (b) 1200 (c) 1400
  40. 40.Best estimate of 24 × 86? (a) 18000 (b) 1800 (c) 180

Answer key

  1. 1200
  2. 1300
  3. 1000
  4. 1200
  5. 700
  6. 6300
  7. 8100
  8. 800
  9. 2500
  10. 3600
  11. 700
  12. 800
  13. 3200
  14. 1100
  15. 6400
  16. 7000
  17. 3200
  18. 1000
  19. 2700
  20. 800
  21. 1500
  22. 400
  23. 600
  24. 3200
  25. 1000
  26. 1300
  27. 200
  28. 1100
  29. 3600
  30. 800
  31. 400
  32. 900
  33. 400
  34. 1100
  35. 600
  36. 1200
  37. 2800
  38. 1000
  39. 1400
  40. 1800

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