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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 42 · 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 84 × 52? (a) 40000 (b) 4000 (c) 400
  2. 2.Best estimate of 435 + 275? (a) 900 (b) 700 (c) 500
  3. 3.Best estimate of 88 × 89? (a) 81000 (b) 8100 (c) 810
  4. 4.Best estimate of 321 + 453? (a) 1000 (b) 800 (c) 600
  5. 5.Best estimate of 71 × 18? (a) 1400 (b) 140 (c) 14000
  6. 6.Best estimate of 63 × 76? (a) 4800 (b) 48000 (c) 480
  7. 7.Best estimate of 40 × 64? (a) 2400 (b) 24000 (c) 240
  8. 8.Best estimate of 449 + 801? (a) 1000 (b) 1400 (c) 1200
  9. 9.Best estimate of 790 + 533? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 36 × 18? (a) 800 (b) 8000 (c) 80
  11. 11.Best estimate of 614 + 805? (a) 1400 (b) 1200 (c) 1600
  12. 12.Best estimate of 816 + 277? (a) 1300 (b) 1100 (c) 900
  13. 13.Best estimate of 46 × 38? (a) 200 (b) 2000 (c) 20000
  14. 14.Best estimate of 96 × 33? (a) 30000 (b) 300 (c) 3000
  15. 15.Best estimate of 33 × 74? (a) 210 (b) 2100 (c) 21000
  16. 16.Best estimate of 49 × 28? (a) 150 (b) 1500 (c) 15000
  17. 17.Best estimate of 97 × 17? (a) 20000 (b) 2000 (c) 200
  18. 18.Best estimate of 67 × 36? (a) 2800 (b) 28000 (c) 280
  19. 19.Best estimate of 23 × 86? (a) 1800 (b) 180 (c) 18000
  20. 20.Best estimate of 727 + 199? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 856 + 238? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 568 + 221? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 453 + 751? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 311 + 662? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 74 × 71? (a) 49000 (b) 490 (c) 4900
  26. 26.Best estimate of 33 × 31? (a) 9000 (b) 900 (c) 90
  27. 27.Best estimate of 170 + 170? (a) 600 (b) 200 (c) 400
  28. 28.Best estimate of 96 × 86? (a) 90000 (b) 9000 (c) 900
  29. 29.Best estimate of 86 × 26? (a) 27000 (b) 2700 (c) 270
  30. 30.Best estimate of 51 × 76? (a) 40000 (b) 4000 (c) 400
  31. 31.Best estimate of 816 + 345? (a) 1300 (b) 1100 (c) 900
  32. 32.Best estimate of 22 × 52? (a) 100 (b) 10000 (c) 1000
  33. 33.Best estimate of 399 + 733? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 32 × 27? (a) 900 (b) 9000 (c) 90
  35. 35.Best estimate of 52 × 87? (a) 45000 (b) 450 (c) 4500
  36. 36.Best estimate of 432 + 647? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 590 + 277? (a) 1100 (b) 700 (c) 900
  38. 38.Best estimate of 97 × 96? (a) 100000 (b) 1000 (c) 10000
  39. 39.Best estimate of 484 + 696? (a) 1000 (b) 1200 (c) 1400
  40. 40.Best estimate of 270 + 863? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 4000
  2. 700
  3. 8100
  4. 800
  5. 1400
  6. 4800
  7. 2400
  8. 1200
  9. 1300
  10. 800
  11. 1400
  12. 1100
  13. 2000
  14. 3000
  15. 2100
  16. 1500
  17. 2000
  18. 2800
  19. 1800
  20. 900
  21. 1100
  22. 800
  23. 1300
  24. 1000
  25. 4900
  26. 900
  27. 400
  28. 9000
  29. 2700
  30. 4000
  31. 1100
  32. 1000
  33. 1100
  34. 900
  35. 4500
  36. 1000
  37. 900
  38. 10000
  39. 1200
  40. 1200

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