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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 419 · 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 40 × 74? (a) 28000 (b) 2800 (c) 280
  2. 2.Best estimate of 565 + 263? (a) 1100 (b) 700 (c) 900
  3. 3.Best estimate of 88 × 16? (a) 18000 (b) 180 (c) 1800
  4. 4.Best estimate of 479 + 778? (a) 1300 (b) 1500 (c) 1100
  5. 5.Best estimate of 42 × 50? (a) 20000 (b) 2000 (c) 200
  6. 6.Best estimate of 746 + 848? (a) 1500 (b) 1700 (c) 1300
  7. 7.Best estimate of 144 + 152? (a) 300 (b) 500 (c) 100
  8. 8.Best estimate of 516 + 300? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 752 + 713? (a) 1300 (b) 1500 (c) 1700
  10. 10.Best estimate of 70 × 24? (a) 1400 (b) 14000 (c) 140
  11. 11.Best estimate of 69 × 70? (a) 490 (b) 49000 (c) 4900
  12. 12.Best estimate of 76 × 77? (a) 6400 (b) 640 (c) 64000
  13. 13.Best estimate of 36 × 50? (a) 200 (b) 20000 (c) 2000
  14. 14.Best estimate of 32 × 39? (a) 1200 (b) 120 (c) 12000
  15. 15.Best estimate of 96 × 64? (a) 600 (b) 6000 (c) 60000
  16. 16.Best estimate of 451 + 212? (a) 700 (b) 500 (c) 900
  17. 17.Best estimate of 66 × 28? (a) 210 (b) 2100 (c) 21000
  18. 18.Best estimate of 18 × 46? (a) 10000 (b) 100 (c) 1000
  19. 19.Best estimate of 53 × 44? (a) 20000 (b) 2000 (c) 200
  20. 20.Best estimate of 86 × 28? (a) 270 (b) 2700 (c) 27000
  21. 21.Best estimate of 49 × 62? (a) 30000 (b) 300 (c) 3000
  22. 22.Best estimate of 428 + 187? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 29 × 47? (a) 15000 (b) 1500 (c) 150
  24. 24.Best estimate of 30 × 47? (a) 15000 (b) 150 (c) 1500
  25. 25.Best estimate of 392 + 782? (a) 1400 (b) 1000 (c) 1200
  26. 26.Best estimate of 68 × 44? (a) 2800 (b) 28000 (c) 280
  27. 27.Best estimate of 19 × 63? (a) 12000 (b) 1200 (c) 120
  28. 28.Best estimate of 317 + 819? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 59 × 22? (a) 120 (b) 1200 (c) 12000
  30. 30.Best estimate of 26 × 49? (a) 1500 (b) 15000 (c) 150
  31. 31.Best estimate of 776 + 423? (a) 1200 (b) 1000 (c) 1400
  32. 32.Best estimate of 396 + 635? (a) 800 (b) 1000 (c) 1200
  33. 33.Best estimate of 801 + 809? (a) 1400 (b) 1600 (c) 1800
  34. 34.Best estimate of 482 + 843? (a) 1300 (b) 1500 (c) 1100
  35. 35.Best estimate of 161 + 779? (a) 800 (b) 1200 (c) 1000
  36. 36.Best estimate of 694 + 859? (a) 1400 (b) 1600 (c) 1800
  37. 37.Best estimate of 16 × 79? (a) 1600 (b) 160 (c) 16000
  38. 38.Best estimate of 48 × 37? (a) 20000 (b) 2000 (c) 200
  39. 39.Best estimate of 168 + 362? (a) 800 (b) 400 (c) 600
  40. 40.Best estimate of 37 × 56? (a) 24000 (b) 240 (c) 2400

Answer key

  1. 2800
  2. 900
  3. 1800
  4. 1300
  5. 2000
  6. 1500
  7. 300
  8. 800
  9. 1500
  10. 1400
  11. 4900
  12. 6400
  13. 2000
  14. 1200
  15. 6000
  16. 700
  17. 2100
  18. 1000
  19. 2000
  20. 2700
  21. 3000
  22. 600
  23. 1500
  24. 1500
  25. 1200
  26. 2800
  27. 1200
  28. 1100
  29. 1200
  30. 1500
  31. 1200
  32. 1000
  33. 1600
  34. 1300
  35. 1000
  36. 1600
  37. 1600
  38. 2000
  39. 600
  40. 2400

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