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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 328 · 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 507 + 127? (a) 600 (b) 800 (c) 400
  2. 2.Best estimate of 586 + 547? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 37 × 56? (a) 240 (b) 24000 (c) 2400
  4. 4.Best estimate of 28 × 50? (a) 1500 (b) 15000 (c) 150
  5. 5.Best estimate of 66 × 49? (a) 35000 (b) 3500 (c) 350
  6. 6.Best estimate of 763 + 282? (a) 1100 (b) 1300 (c) 900
  7. 7.Best estimate of 174 + 266? (a) 700 (b) 300 (c) 500
  8. 8.Best estimate of 31 × 70? (a) 21000 (b) 210 (c) 2100
  9. 9.Best estimate of 96 × 98? (a) 1000 (b) 10000 (c) 100000
  10. 10.Best estimate of 36 × 62? (a) 2400 (b) 24000 (c) 240
  11. 11.Best estimate of 20 × 60? (a) 12000 (b) 120 (c) 1200
  12. 12.Best estimate of 648 + 180? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 366 + 868? (a) 1300 (b) 1500 (c) 1100
  14. 14.Best estimate of 818 + 268? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 18 × 18? (a) 400 (b) 40 (c) 4000
  16. 16.Best estimate of 78 × 89? (a) 7200 (b) 720 (c) 72000
  17. 17.Best estimate of 648 + 842? (a) 1200 (b) 1400 (c) 1600
  18. 18.Best estimate of 38 × 46? (a) 20000 (b) 2000 (c) 200
  19. 19.Best estimate of 21 × 58? (a) 12000 (b) 1200 (c) 120
  20. 20.Best estimate of 555 + 176? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 23 × 83? (a) 16000 (b) 160 (c) 1600
  22. 22.Best estimate of 44 × 13? (a) 40 (b) 4000 (c) 400
  23. 23.Best estimate of 567 + 813? (a) 1200 (b) 1400 (c) 1600
  24. 24.Best estimate of 815 + 655? (a) 1500 (b) 1300 (c) 1700
  25. 25.Best estimate of 429 + 717? (a) 1100 (b) 900 (c) 1300
  26. 26.Best estimate of 228 + 720? (a) 1100 (b) 900 (c) 700
  27. 27.Best estimate of 773 + 493? (a) 1300 (b) 1100 (c) 1500
  28. 28.Best estimate of 773 + 592? (a) 1400 (b) 1600 (c) 1200
  29. 29.Best estimate of 815 + 543? (a) 1500 (b) 1300 (c) 1100
  30. 30.Best estimate of 491 + 381? (a) 900 (b) 1100 (c) 700
  31. 31.Best estimate of 465 + 865? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 284 + 537? (a) 1000 (b) 600 (c) 800
  33. 33.Best estimate of 69 × 87? (a) 63000 (b) 6300 (c) 630
  34. 34.Best estimate of 828 + 525? (a) 1500 (b) 1100 (c) 1300
  35. 35.Best estimate of 661 + 362? (a) 1300 (b) 900 (c) 1100
  36. 36.Best estimate of 72 × 73? (a) 49000 (b) 4900 (c) 490
  37. 37.Best estimate of 660 + 618? (a) 1300 (b) 1500 (c) 1100
  38. 38.Best estimate of 665 + 483? (a) 1400 (b) 1000 (c) 1200
  39. 39.Best estimate of 651 + 288? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 42 × 96? (a) 400 (b) 4000 (c) 40000

Answer key

  1. 600
  2. 1100
  3. 2400
  4. 1500
  5. 3500
  6. 1100
  7. 500
  8. 2100
  9. 10000
  10. 2400
  11. 1200
  12. 800
  13. 1300
  14. 1100
  15. 400
  16. 7200
  17. 1400
  18. 2000
  19. 1200
  20. 800
  21. 1600
  22. 400
  23. 1400
  24. 1500
  25. 1100
  26. 900
  27. 1300
  28. 1400
  29. 1300
  30. 900
  31. 1400
  32. 800
  33. 6300
  34. 1300
  35. 1100
  36. 4900
  37. 1300
  38. 1200
  39. 1000
  40. 4000

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