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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 564 · 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 351 + 565? (a) 1000 (b) 1200 (c) 800
  2. 2.Best estimate of 70 × 40? (a) 28000 (b) 2800 (c) 280
  3. 3.Best estimate of 521 + 131? (a) 400 (b) 800 (c) 600
  4. 4.Best estimate of 308 + 289? (a) 600 (b) 400 (c) 800
  5. 5.Best estimate of 87 × 28? (a) 270 (b) 27000 (c) 2700
  6. 6.Best estimate of 96 × 26? (a) 30000 (b) 3000 (c) 300
  7. 7.Best estimate of 16 × 66? (a) 1400 (b) 14000 (c) 140
  8. 8.Best estimate of 33 × 13? (a) 3000 (b) 300 (c) 30
  9. 9.Best estimate of 53 × 87? (a) 4500 (b) 45000 (c) 450
  10. 10.Best estimate of 173 + 779? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 765 + 296? (a) 900 (b) 1100 (c) 1300
  12. 12.Best estimate of 481 + 637? (a) 900 (b) 1300 (c) 1100
  13. 13.Best estimate of 848 + 122? (a) 700 (b) 1100 (c) 900
  14. 14.Best estimate of 457 + 800? (a) 1100 (b) 1500 (c) 1300
  15. 15.Best estimate of 93 × 19? (a) 18000 (b) 180 (c) 1800
  16. 16.Best estimate of 40 × 63? (a) 2400 (b) 240 (c) 24000
  17. 17.Best estimate of 82 × 32? (a) 240 (b) 24000 (c) 2400
  18. 18.Best estimate of 433 + 163? (a) 600 (b) 800 (c) 400
  19. 19.Best estimate of 80 × 22? (a) 16000 (b) 1600 (c) 160
  20. 20.Best estimate of 579 + 763? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 31 × 46? (a) 150 (b) 15000 (c) 1500
  22. 22.Best estimate of 612 + 848? (a) 1400 (b) 1600 (c) 1200
  23. 23.Best estimate of 381 + 203? (a) 800 (b) 600 (c) 400
  24. 24.Best estimate of 177 + 186? (a) 600 (b) 200 (c) 400
  25. 25.Best estimate of 174 + 381? (a) 400 (b) 600 (c) 800
  26. 26.Best estimate of 46 × 14? (a) 500 (b) 5000 (c) 50
  27. 27.Best estimate of 91 × 86? (a) 81000 (b) 8100 (c) 810
  28. 28.Best estimate of 846 + 291? (a) 1100 (b) 900 (c) 1300
  29. 29.Best estimate of 437 + 651? (a) 1100 (b) 1300 (c) 900
  30. 30.Best estimate of 13 × 16? (a) 20 (b) 2000 (c) 200
  31. 31.Best estimate of 364 + 329? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 17 × 34? (a) 6000 (b) 600 (c) 60
  33. 33.Best estimate of 26 × 36? (a) 1200 (b) 12000 (c) 120
  34. 34.Best estimate of 231 + 693? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 423 + 180? (a) 400 (b) 800 (c) 600
  36. 36.Best estimate of 261 + 127? (a) 600 (b) 400 (c) 200
  37. 37.Best estimate of 604 + 228? (a) 600 (b) 800 (c) 1000
  38. 38.Best estimate of 72 × 26? (a) 210 (b) 21000 (c) 2100
  39. 39.Best estimate of 48 × 18? (a) 1000 (b) 10000 (c) 100
  40. 40.Best estimate of 493 + 217? (a) 500 (b) 900 (c) 700

Answer key

  1. 1000
  2. 2800
  3. 600
  4. 600
  5. 2700
  6. 3000
  7. 1400
  8. 300
  9. 4500
  10. 1000
  11. 1100
  12. 1100
  13. 900
  14. 1300
  15. 1800
  16. 2400
  17. 2400
  18. 600
  19. 1600
  20. 1400
  21. 1500
  22. 1400
  23. 600
  24. 400
  25. 600
  26. 500
  27. 8100
  28. 1100
  29. 1100
  30. 200
  31. 700
  32. 600
  33. 1200
  34. 900
  35. 600
  36. 400
  37. 800
  38. 2100
  39. 1000
  40. 700

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