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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 957 · 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 214 + 613? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 447 + 202? (a) 600 (b) 800 (c) 400
  3. 3.Best estimate of 27 × 18? (a) 6000 (b) 60 (c) 600
  4. 4.Best estimate of 768 + 220? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 138 + 841? (a) 700 (b) 900 (c) 1100
  6. 6.Best estimate of 72 × 81? (a) 56000 (b) 5600 (c) 560
  7. 7.Best estimate of 39 × 21? (a) 800 (b) 8000 (c) 80
  8. 8.Best estimate of 97 × 69? (a) 7000 (b) 700 (c) 70000
  9. 9.Best estimate of 272 + 392? (a) 700 (b) 900 (c) 500
  10. 10.Best estimate of 539 + 235? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 340 + 152? (a) 700 (b) 500 (c) 300
  12. 12.Best estimate of 16 × 57? (a) 1200 (b) 12000 (c) 120
  13. 13.Best estimate of 354 + 779? (a) 1200 (b) 1000 (c) 1400
  14. 14.Best estimate of 26 × 70? (a) 21000 (b) 2100 (c) 210
  15. 15.Best estimate of 93 × 74? (a) 630 (b) 6300 (c) 63000
  16. 16.Best estimate of 16 × 78? (a) 160 (b) 1600 (c) 16000
  17. 17.Best estimate of 603 + 686? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 66 × 60? (a) 420 (b) 4200 (c) 42000
  19. 19.Best estimate of 46 × 46? (a) 2500 (b) 25000 (c) 250
  20. 20.Best estimate of 47 × 21? (a) 10000 (b) 100 (c) 1000
  21. 21.Best estimate of 613 + 593? (a) 1200 (b) 1000 (c) 1400
  22. 22.Best estimate of 614 + 255? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 78 × 76? (a) 640 (b) 64000 (c) 6400
  24. 24.Best estimate of 22 × 74? (a) 140 (b) 14000 (c) 1400
  25. 25.Best estimate of 60 × 76? (a) 480 (b) 4800 (c) 48000
  26. 26.Best estimate of 89 × 26? (a) 270 (b) 2700 (c) 27000
  27. 27.Best estimate of 61 × 53? (a) 3000 (b) 30000 (c) 300
  28. 28.Best estimate of 80 × 27? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 828 + 506? (a) 1100 (b) 1300 (c) 1500
  30. 30.Best estimate of 38 × 76? (a) 32000 (b) 320 (c) 3200
  31. 31.Best estimate of 64 × 57? (a) 360 (b) 36000 (c) 3600
  32. 32.Best estimate of 148 + 265? (a) 400 (b) 600 (c) 200
  33. 33.Best estimate of 311 + 273? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 33 × 71? (a) 2100 (b) 21000 (c) 210
  35. 35.Best estimate of 201 + 842? (a) 800 (b) 1200 (c) 1000
  36. 36.Best estimate of 36 × 14? (a) 4000 (b) 400 (c) 40
  37. 37.Best estimate of 195 + 643? (a) 800 (b) 1000 (c) 600
  38. 38.Best estimate of 40 × 28? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 36 × 53? (a) 200 (b) 2000 (c) 20000
  40. 40.Best estimate of 26 × 57? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 800
  2. 600
  3. 600
  4. 1000
  5. 900
  6. 5600
  7. 800
  8. 7000
  9. 700
  10. 700
  11. 500
  12. 1200
  13. 1200
  14. 2100
  15. 6300
  16. 1600
  17. 1300
  18. 4200
  19. 2500
  20. 1000
  21. 1200
  22. 900
  23. 6400
  24. 1400
  25. 4800
  26. 2700
  27. 3000
  28. 2400
  29. 1300
  30. 3200
  31. 3600
  32. 400
  33. 600
  34. 2100
  35. 1000
  36. 400
  37. 800
  38. 1200
  39. 2000
  40. 1800

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