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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 653 · 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 20 × 32? (a) 60 (b) 6000 (c) 600
  2. 2.Best estimate of 78 × 90? (a) 7200 (b) 720 (c) 72000
  3. 3.Best estimate of 91 × 24? (a) 1800 (b) 18000 (c) 180
  4. 4.Best estimate of 127 + 299? (a) 400 (b) 200 (c) 600
  5. 5.Best estimate of 63 × 38? (a) 240 (b) 24000 (c) 2400
  6. 6.Best estimate of 47 × 66? (a) 3500 (b) 350 (c) 35000
  7. 7.Best estimate of 290 + 856? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 168 + 632? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 631 + 394? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 62 × 16? (a) 120 (b) 1200 (c) 12000
  11. 11.Best estimate of 34 × 94? (a) 27000 (b) 2700 (c) 270
  12. 12.Best estimate of 288 + 467? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 727 + 696? (a) 1400 (b) 1200 (c) 1600
  14. 14.Best estimate of 86 × 24? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 76 × 52? (a) 4000 (b) 40000 (c) 400
  16. 16.Best estimate of 149 + 623? (a) 900 (b) 700 (c) 500
  17. 17.Best estimate of 377 + 378? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 82 × 40? (a) 3200 (b) 32000 (c) 320
  19. 19.Best estimate of 874 + 181? (a) 1300 (b) 900 (c) 1100
  20. 20.Best estimate of 747 + 544? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 488 + 570? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 144 + 140? (a) 200 (b) 400 (c) 0
  23. 23.Best estimate of 839 + 541? (a) 1500 (b) 1300 (c) 1100
  24. 24.Best estimate of 486 + 394? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 31 × 86? (a) 27000 (b) 270 (c) 2700
  26. 26.Best estimate of 64 × 30? (a) 1800 (b) 180 (c) 18000
  27. 27.Best estimate of 19 × 13? (a) 200 (b) 2000 (c) 20
  28. 28.Best estimate of 465 + 552? (a) 1100 (b) 900 (c) 1300
  29. 29.Best estimate of 383 + 583? (a) 1000 (b) 1200 (c) 800
  30. 30.Best estimate of 94 × 72? (a) 630 (b) 63000 (c) 6300
  31. 31.Best estimate of 578 + 790? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 435 + 524? (a) 900 (b) 700 (c) 1100
  33. 33.Best estimate of 449 + 496? (a) 900 (b) 1100 (c) 700
  34. 34.Best estimate of 12 × 81? (a) 80 (b) 8000 (c) 800
  35. 35.Best estimate of 39 × 81? (a) 3200 (b) 320 (c) 32000
  36. 36.Best estimate of 463 + 337? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 78 × 77? (a) 64000 (b) 640 (c) 6400
  38. 38.Best estimate of 336 + 266? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 76 × 54? (a) 40000 (b) 400 (c) 4000
  40. 40.Best estimate of 52 × 58? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 600
  2. 7200
  3. 1800
  4. 400
  5. 2400
  6. 3500
  7. 1200
  8. 800
  9. 1000
  10. 1200
  11. 2700
  12. 800
  13. 1400
  14. 1800
  15. 4000
  16. 700
  17. 800
  18. 3200
  19. 1100
  20. 1200
  21. 1100
  22. 200
  23. 1300
  24. 900
  25. 2700
  26. 1800
  27. 200
  28. 1100
  29. 1000
  30. 6300
  31. 1400
  32. 900
  33. 900
  34. 800
  35. 3200
  36. 800
  37. 6400
  38. 600
  39. 4000
  40. 3000

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