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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 818 · 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 81 × 70? (a) 560 (b) 56000 (c) 5600
  2. 2.Best estimate of 393 + 462? (a) 1100 (b) 900 (c) 700
  3. 3.Best estimate of 158 + 347? (a) 300 (b) 500 (c) 700
  4. 4.Best estimate of 62 × 92? (a) 5400 (b) 54000 (c) 540
  5. 5.Best estimate of 74 × 14? (a) 70 (b) 7000 (c) 700
  6. 6.Best estimate of 684 + 726? (a) 1400 (b) 1200 (c) 1600
  7. 7.Best estimate of 36 × 50? (a) 20000 (b) 200 (c) 2000
  8. 8.Best estimate of 26 × 42? (a) 120 (b) 1200 (c) 12000
  9. 9.Best estimate of 48 × 96? (a) 500 (b) 5000 (c) 50000
  10. 10.Best estimate of 67 × 12? (a) 70 (b) 700 (c) 7000
  11. 11.Best estimate of 52 × 88? (a) 45000 (b) 450 (c) 4500
  12. 12.Best estimate of 86 × 14? (a) 9000 (b) 90 (c) 900
  13. 13.Best estimate of 46 × 39? (a) 20000 (b) 2000 (c) 200
  14. 14.Best estimate of 31 × 74? (a) 2100 (b) 21000 (c) 210
  15. 15.Best estimate of 18 × 30? (a) 60 (b) 6000 (c) 600
  16. 16.Best estimate of 319 + 647? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 228 + 554? (a) 800 (b) 600 (c) 1000
  18. 18.Best estimate of 626 + 317? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 23 × 51? (a) 1000 (b) 10000 (c) 100
  20. 20.Best estimate of 82 × 27? (a) 240 (b) 2400 (c) 24000
  21. 21.Best estimate of 19 × 29? (a) 6000 (b) 600 (c) 60
  22. 22.Best estimate of 62 × 14? (a) 60 (b) 600 (c) 6000
  23. 23.Best estimate of 428 + 829? (a) 1000 (b) 1200 (c) 1400
  24. 24.Best estimate of 26 × 16? (a) 60 (b) 600 (c) 6000
  25. 25.Best estimate of 21 × 78? (a) 1600 (b) 16000 (c) 160
  26. 26.Best estimate of 29 × 30? (a) 90 (b) 900 (c) 9000
  27. 27.Best estimate of 855 + 453? (a) 1600 (b) 1400 (c) 1200
  28. 28.Best estimate of 314 + 687? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 79 × 16? (a) 160 (b) 1600 (c) 16000
  30. 30.Best estimate of 633 + 708? (a) 1300 (b) 1100 (c) 1500
  31. 31.Best estimate of 127 + 546? (a) 400 (b) 800 (c) 600
  32. 32.Best estimate of 26 × 56? (a) 180 (b) 1800 (c) 18000
  33. 33.Best estimate of 400 + 659? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 296 + 807? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 391 + 685? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 16 × 76? (a) 1600 (b) 16000 (c) 160
  37. 37.Best estimate of 92 × 48? (a) 4500 (b) 45000 (c) 450
  38. 38.Best estimate of 156 + 506? (a) 500 (b) 700 (c) 900
  39. 39.Best estimate of 27 × 30? (a) 9000 (b) 900 (c) 90
  40. 40.Best estimate of 799 + 427? (a) 1200 (b) 1000 (c) 1400

Answer key

  1. 5600
  2. 900
  3. 500
  4. 5400
  5. 700
  6. 1400
  7. 2000
  8. 1200
  9. 5000
  10. 700
  11. 4500
  12. 900
  13. 2000
  14. 2100
  15. 600
  16. 900
  17. 800
  18. 900
  19. 1000
  20. 2400
  21. 600
  22. 600
  23. 1200
  24. 600
  25. 1600
  26. 900
  27. 1400
  28. 1000
  29. 1600
  30. 1300
  31. 600
  32. 1800
  33. 1100
  34. 1100
  35. 1100
  36. 1600
  37. 4500
  38. 700
  39. 900
  40. 1200

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