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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 464 · 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 844 + 326? (a) 900 (b) 1100 (c) 1300
  2. 2.Best estimate of 56 × 36? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 531 + 576? (a) 1100 (b) 1300 (c) 900
  4. 4.Best estimate of 72 × 31? (a) 210 (b) 2100 (c) 21000
  5. 5.Best estimate of 496 + 575? (a) 1300 (b) 900 (c) 1100
  6. 6.Best estimate of 49 × 29? (a) 15000 (b) 1500 (c) 150
  7. 7.Best estimate of 16 × 79? (a) 16000 (b) 160 (c) 1600
  8. 8.Best estimate of 42 × 36? (a) 1600 (b) 160 (c) 16000
  9. 9.Best estimate of 254 + 261? (a) 600 (b) 800 (c) 400
  10. 10.Best estimate of 875 + 136? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 354 + 213? (a) 400 (b) 800 (c) 600
  12. 12.Best estimate of 159 + 129? (a) 300 (b) 100 (c) 500
  13. 13.Best estimate of 737 + 235? (a) 700 (b) 1100 (c) 900
  14. 14.Best estimate of 309 + 143? (a) 200 (b) 400 (c) 600
  15. 15.Best estimate of 441 + 279? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 82 × 63? (a) 4800 (b) 48000 (c) 480
  17. 17.Best estimate of 340 + 199? (a) 700 (b) 300 (c) 500
  18. 18.Best estimate of 340 + 621? (a) 700 (b) 900 (c) 1100
  19. 19.Best estimate of 56 × 52? (a) 30000 (b) 3000 (c) 300
  20. 20.Best estimate of 48 × 19? (a) 10000 (b) 100 (c) 1000
  21. 21.Best estimate of 793 + 407? (a) 1400 (b) 1200 (c) 1000
  22. 22.Best estimate of 623 + 179? (a) 800 (b) 1000 (c) 600
  23. 23.Best estimate of 23 × 67? (a) 14000 (b) 140 (c) 1400
  24. 24.Best estimate of 53 × 80? (a) 40000 (b) 4000 (c) 400
  25. 25.Best estimate of 848 + 880? (a) 1900 (b) 1500 (c) 1700
  26. 26.Best estimate of 519 + 726? (a) 1000 (b) 1400 (c) 1200
  27. 27.Best estimate of 195 + 799? (a) 1000 (b) 800 (c) 1200
  28. 28.Best estimate of 73 × 62? (a) 4200 (b) 420 (c) 42000
  29. 29.Best estimate of 14 × 24? (a) 200 (b) 2000 (c) 20
  30. 30.Best estimate of 67 × 20? (a) 1400 (b) 14000 (c) 140
  31. 31.Best estimate of 19 × 27? (a) 600 (b) 6000 (c) 60
  32. 32.Best estimate of 280 + 314? (a) 600 (b) 400 (c) 800
  33. 33.Best estimate of 501 + 529? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 76 × 28? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 308 + 514? (a) 1000 (b) 800 (c) 600
  36. 36.Best estimate of 21 × 39? (a) 800 (b) 8000 (c) 80
  37. 37.Best estimate of 37 × 16? (a) 8000 (b) 800 (c) 80
  38. 38.Best estimate of 96 × 97? (a) 1000 (b) 10000 (c) 100000
  39. 39.Best estimate of 56 × 70? (a) 4200 (b) 42000 (c) 420
  40. 40.Best estimate of 148 + 187? (a) 500 (b) 300 (c) 100

Answer key

  1. 1100
  2. 2400
  3. 1100
  4. 2100
  5. 1100
  6. 1500
  7. 1600
  8. 1600
  9. 600
  10. 1000
  11. 600
  12. 300
  13. 900
  14. 400
  15. 700
  16. 4800
  17. 500
  18. 900
  19. 3000
  20. 1000
  21. 1200
  22. 800
  23. 1400
  24. 4000
  25. 1700
  26. 1200
  27. 1000
  28. 4200
  29. 200
  30. 1400
  31. 600
  32. 600
  33. 1000
  34. 2400
  35. 800
  36. 800
  37. 800
  38. 10000
  39. 4200
  40. 300

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