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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 378 · 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 855 + 407? (a) 1100 (b) 1500 (c) 1300
  2. 2.Best estimate of 587 + 279? (a) 700 (b) 1100 (c) 900
  3. 3.Best estimate of 77 × 50? (a) 40000 (b) 4000 (c) 400
  4. 4.Best estimate of 482 + 362? (a) 1100 (b) 700 (c) 900
  5. 5.Best estimate of 37 × 47? (a) 2000 (b) 200 (c) 20000
  6. 6.Best estimate of 753 + 700? (a) 1300 (b) 1700 (c) 1500
  7. 7.Best estimate of 98 × 63? (a) 600 (b) 60000 (c) 6000
  8. 8.Best estimate of 18 × 78? (a) 16000 (b) 160 (c) 1600
  9. 9.Best estimate of 469 + 613? (a) 900 (b) 1300 (c) 1100
  10. 10.Best estimate of 687 + 644? (a) 1500 (b) 1300 (c) 1100
  11. 11.Best estimate of 50 × 76? (a) 400 (b) 40000 (c) 4000
  12. 12.Best estimate of 593 + 665? (a) 1300 (b) 1100 (c) 1500
  13. 13.Best estimate of 243 + 545? (a) 900 (b) 700 (c) 500
  14. 14.Best estimate of 88 × 37? (a) 36000 (b) 3600 (c) 360
  15. 15.Best estimate of 38 × 27? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 806 + 268? (a) 900 (b) 1100 (c) 1300
  17. 17.Best estimate of 41 × 49? (a) 2000 (b) 20000 (c) 200
  18. 18.Best estimate of 181 + 465? (a) 500 (b) 700 (c) 900
  19. 19.Best estimate of 16 × 54? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 14 × 67? (a) 70 (b) 700 (c) 7000
  21. 21.Best estimate of 32 × 42? (a) 120 (b) 12000 (c) 1200
  22. 22.Best estimate of 47 × 33? (a) 150 (b) 15000 (c) 1500
  23. 23.Best estimate of 60 × 88? (a) 54000 (b) 540 (c) 5400
  24. 24.Best estimate of 535 + 380? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 372 + 127? (a) 700 (b) 300 (c) 500
  26. 26.Best estimate of 38 × 36? (a) 16000 (b) 160 (c) 1600
  27. 27.Best estimate of 36 × 17? (a) 80 (b) 8000 (c) 800
  28. 28.Best estimate of 28 × 70? (a) 2100 (b) 210 (c) 21000
  29. 29.Best estimate of 480 + 422? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 316 + 315? (a) 800 (b) 600 (c) 400
  31. 31.Best estimate of 97 × 51? (a) 5000 (b) 500 (c) 50000
  32. 32.Best estimate of 68 × 24? (a) 140 (b) 14000 (c) 1400
  33. 33.Best estimate of 72 × 21? (a) 14000 (b) 140 (c) 1400
  34. 34.Best estimate of 98 × 23? (a) 200 (b) 2000 (c) 20000
  35. 35.Best estimate of 23 × 46? (a) 1000 (b) 10000 (c) 100
  36. 36.Best estimate of 513 + 521? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 92 × 64? (a) 540 (b) 5400 (c) 54000
  38. 38.Best estimate of 63 × 76? (a) 48000 (b) 480 (c) 4800
  39. 39.Best estimate of 32 × 86? (a) 27000 (b) 2700 (c) 270
  40. 40.Best estimate of 841 + 403? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 1300
  2. 900
  3. 4000
  4. 900
  5. 2000
  6. 1500
  7. 6000
  8. 1600
  9. 1100
  10. 1300
  11. 4000
  12. 1300
  13. 700
  14. 3600
  15. 1200
  16. 1100
  17. 2000
  18. 700
  19. 1000
  20. 700
  21. 1200
  22. 1500
  23. 5400
  24. 900
  25. 500
  26. 1600
  27. 800
  28. 2100
  29. 900
  30. 600
  31. 5000
  32. 1400
  33. 1400
  34. 2000
  35. 1000
  36. 1000
  37. 5400
  38. 4800
  39. 2700
  40. 1200

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