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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 325 · 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 36 × 19? (a) 8000 (b) 80 (c) 800
  2. 2.Best estimate of 96 × 36? (a) 400 (b) 40000 (c) 4000
  3. 3.Best estimate of 71 × 89? (a) 6300 (b) 63000 (c) 630
  4. 4.Best estimate of 50 × 34? (a) 150 (b) 1500 (c) 15000
  5. 5.Best estimate of 30 × 82? (a) 2400 (b) 240 (c) 24000
  6. 6.Best estimate of 609 + 332? (a) 700 (b) 900 (c) 1100
  7. 7.Best estimate of 293 + 266? (a) 400 (b) 800 (c) 600
  8. 8.Best estimate of 46 × 90? (a) 4500 (b) 45000 (c) 450
  9. 9.Best estimate of 60 × 53? (a) 3000 (b) 30000 (c) 300
  10. 10.Best estimate of 122 + 134? (a) 400 (b) 200 (c) 0
  11. 11.Best estimate of 28 × 87? (a) 2700 (b) 27000 (c) 270
  12. 12.Best estimate of 367 + 239? (a) 800 (b) 600 (c) 400
  13. 13.Best estimate of 31 × 43? (a) 1200 (b) 12000 (c) 120
  14. 14.Best estimate of 374 + 344? (a) 900 (b) 700 (c) 500
  15. 15.Best estimate of 46 × 27? (a) 15000 (b) 150 (c) 1500
  16. 16.Best estimate of 76 × 97? (a) 800 (b) 80000 (c) 8000
  17. 17.Best estimate of 17 × 70? (a) 140 (b) 14000 (c) 1400
  18. 18.Best estimate of 57 × 77? (a) 480 (b) 48000 (c) 4800
  19. 19.Best estimate of 79 × 26? (a) 24000 (b) 2400 (c) 240
  20. 20.Best estimate of 436 + 519? (a) 700 (b) 1100 (c) 900
  21. 21.Best estimate of 637 + 386? (a) 1000 (b) 800 (c) 1200
  22. 22.Best estimate of 670 + 126? (a) 600 (b) 800 (c) 1000
  23. 23.Best estimate of 743 + 705? (a) 1200 (b) 1600 (c) 1400
  24. 24.Best estimate of 234 + 799? (a) 1000 (b) 800 (c) 1200
  25. 25.Best estimate of 310 + 310? (a) 800 (b) 400 (c) 600
  26. 26.Best estimate of 24 × 50? (a) 10000 (b) 100 (c) 1000
  27. 27.Best estimate of 88 × 30? (a) 27000 (b) 2700 (c) 270
  28. 28.Best estimate of 48 × 19? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 36 × 40? (a) 160 (b) 16000 (c) 1600
  30. 30.Best estimate of 53 × 69? (a) 3500 (b) 35000 (c) 350
  31. 31.Best estimate of 96 × 80? (a) 80000 (b) 8000 (c) 800
  32. 32.Best estimate of 844 + 402? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 612 + 802? (a) 1600 (b) 1200 (c) 1400
  34. 34.Best estimate of 36 × 52? (a) 20000 (b) 200 (c) 2000
  35. 35.Best estimate of 76 × 93? (a) 7200 (b) 72000 (c) 720
  36. 36.Best estimate of 865 + 459? (a) 1600 (b) 1200 (c) 1400
  37. 37.Best estimate of 159 + 166? (a) 600 (b) 400 (c) 200
  38. 38.Best estimate of 823 + 591? (a) 1600 (b) 1200 (c) 1400
  39. 39.Best estimate of 160 + 811? (a) 800 (b) 1200 (c) 1000
  40. 40.Best estimate of 26 × 12? (a) 30 (b) 300 (c) 3000

Answer key

  1. 800
  2. 4000
  3. 6300
  4. 1500
  5. 2400
  6. 900
  7. 600
  8. 4500
  9. 3000
  10. 200
  11. 2700
  12. 600
  13. 1200
  14. 700
  15. 1500
  16. 8000
  17. 1400
  18. 4800
  19. 2400
  20. 900
  21. 1000
  22. 800
  23. 1400
  24. 1000
  25. 600
  26. 1000
  27. 2700
  28. 1000
  29. 1600
  30. 3500
  31. 8000
  32. 1200
  33. 1400
  34. 2000
  35. 7200
  36. 1400
  37. 400
  38. 1400
  39. 1000
  40. 300

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