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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 126 · 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 77 × 34? (a) 240 (b) 2400 (c) 24000
  2. 2.Best estimate of 591 + 824? (a) 1400 (b) 1600 (c) 1200
  3. 3.Best estimate of 21 × 82? (a) 16000 (b) 1600 (c) 160
  4. 4.Best estimate of 49 × 71? (a) 350 (b) 35000 (c) 3500
  5. 5.Best estimate of 223 + 210? (a) 400 (b) 200 (c) 600
  6. 6.Best estimate of 147 + 742? (a) 1000 (b) 600 (c) 800
  7. 7.Best estimate of 21 × 21? (a) 400 (b) 4000 (c) 40
  8. 8.Best estimate of 44 × 41? (a) 16000 (b) 1600 (c) 160
  9. 9.Best estimate of 53 × 96? (a) 50000 (b) 5000 (c) 500
  10. 10.Best estimate of 22 × 86? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 43 × 26? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 276 + 494? (a) 600 (b) 800 (c) 1000
  13. 13.Best estimate of 34 × 47? (a) 1500 (b) 15000 (c) 150
  14. 14.Best estimate of 290 + 711? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 815 + 287? (a) 900 (b) 1100 (c) 1300
  16. 16.Best estimate of 705 + 528? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 620 + 879? (a) 1300 (b) 1500 (c) 1700
  18. 18.Best estimate of 726 + 379? (a) 900 (b) 1300 (c) 1100
  19. 19.Best estimate of 867 + 192? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 331 + 310? (a) 400 (b) 600 (c) 800
  21. 21.Best estimate of 22 × 21? (a) 40 (b) 400 (c) 4000
  22. 22.Best estimate of 877 + 672? (a) 1600 (b) 1800 (c) 1400
  23. 23.Best estimate of 406 + 307? (a) 900 (b) 700 (c) 500
  24. 24.Best estimate of 353 + 533? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 820 + 154? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 720 + 298? (a) 800 (b) 1000 (c) 1200
  27. 27.Best estimate of 46 × 49? (a) 25000 (b) 250 (c) 2500
  28. 28.Best estimate of 83 × 22? (a) 16000 (b) 160 (c) 1600
  29. 29.Best estimate of 329 + 602? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 19 × 16? (a) 4000 (b) 400 (c) 40
  31. 31.Best estimate of 71 × 74? (a) 490 (b) 4900 (c) 49000
  32. 32.Best estimate of 30 × 96? (a) 300 (b) 30000 (c) 3000
  33. 33.Best estimate of 73 × 51? (a) 35000 (b) 3500 (c) 350
  34. 34.Best estimate of 254 + 836? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 451 + 857? (a) 1400 (b) 1200 (c) 1600
  36. 36.Best estimate of 623 + 417? (a) 1000 (b) 800 (c) 1200
  37. 37.Best estimate of 77 × 37? (a) 3200 (b) 32000 (c) 320
  38. 38.Best estimate of 86 × 97? (a) 900 (b) 90000 (c) 9000
  39. 39.Best estimate of 735 + 545? (a) 1200 (b) 1000 (c) 1400
  40. 40.Best estimate of 36 × 53? (a) 2000 (b) 200 (c) 20000

Answer key

  1. 2400
  2. 1400
  3. 1600
  4. 3500
  5. 400
  6. 800
  7. 400
  8. 1600
  9. 5000
  10. 1800
  11. 1200
  12. 800
  13. 1500
  14. 1000
  15. 1100
  16. 1200
  17. 1500
  18. 1100
  19. 1100
  20. 600
  21. 400
  22. 1600
  23. 700
  24. 900
  25. 1000
  26. 1000
  27. 2500
  28. 1600
  29. 900
  30. 400
  31. 4900
  32. 3000
  33. 3500
  34. 1100
  35. 1400
  36. 1000
  37. 3200
  38. 9000
  39. 1200
  40. 2000

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