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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 127 · 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 39 × 62? (a) 2400 (b) 240 (c) 24000
  2. 2.Best estimate of 30 × 41? (a) 120 (b) 12000 (c) 1200
  3. 3.Best estimate of 214 + 215? (a) 400 (b) 600 (c) 200
  4. 4.Best estimate of 594 + 123? (a) 700 (b) 500 (c) 900
  5. 5.Best estimate of 14 × 74? (a) 700 (b) 70 (c) 7000
  6. 6.Best estimate of 48 × 93? (a) 45000 (b) 450 (c) 4500
  7. 7.Best estimate of 80 × 21? (a) 16000 (b) 1600 (c) 160
  8. 8.Best estimate of 282 + 407? (a) 900 (b) 500 (c) 700
  9. 9.Best estimate of 299 + 812? (a) 1100 (b) 900 (c) 1300
  10. 10.Best estimate of 209 + 371? (a) 600 (b) 400 (c) 800
  11. 11.Best estimate of 654 + 192? (a) 700 (b) 900 (c) 1100
  12. 12.Best estimate of 46 × 58? (a) 3000 (b) 300 (c) 30000
  13. 13.Best estimate of 502 + 799? (a) 1300 (b) 1500 (c) 1100
  14. 14.Best estimate of 293 + 765? (a) 900 (b) 1100 (c) 1300
  15. 15.Best estimate of 152 + 330? (a) 700 (b) 300 (c) 500
  16. 16.Best estimate of 261 + 302? (a) 800 (b) 600 (c) 400
  17. 17.Best estimate of 36 × 40? (a) 16000 (b) 1600 (c) 160
  18. 18.Best estimate of 402 + 594? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 756 + 551? (a) 1200 (b) 1400 (c) 1600
  20. 20.Best estimate of 451 + 184? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 137 + 715? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 62 × 72? (a) 4200 (b) 420 (c) 42000
  23. 23.Best estimate of 97 × 89? (a) 900 (b) 90000 (c) 9000
  24. 24.Best estimate of 51 × 80? (a) 400 (b) 40000 (c) 4000
  25. 25.Best estimate of 20 × 91? (a) 1800 (b) 180 (c) 18000
  26. 26.Best estimate of 42 × 79? (a) 32000 (b) 320 (c) 3200
  27. 27.Best estimate of 13 × 78? (a) 80 (b) 8000 (c) 800
  28. 28.Best estimate of 656 + 152? (a) 900 (b) 1100 (c) 700
  29. 29.Best estimate of 57 × 18? (a) 1200 (b) 12000 (c) 120
  30. 30.Best estimate of 92 × 27? (a) 2700 (b) 27000 (c) 270
  31. 31.Best estimate of 430 + 310? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 863 + 292? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 74 × 54? (a) 350 (b) 35000 (c) 3500
  34. 34.Best estimate of 71 × 54? (a) 350 (b) 3500 (c) 35000
  35. 35.Best estimate of 130 + 169? (a) 300 (b) 100 (c) 500
  36. 36.Best estimate of 50 × 59? (a) 30000 (b) 300 (c) 3000
  37. 37.Best estimate of 666 + 239? (a) 1100 (b) 700 (c) 900
  38. 38.Best estimate of 27 × 51? (a) 15000 (b) 1500 (c) 150
  39. 39.Best estimate of 96 × 12? (a) 10000 (b) 1000 (c) 100
  40. 40.Best estimate of 590 + 508? (a) 900 (b) 1300 (c) 1100

Answer key

  1. 2400
  2. 1200
  3. 400
  4. 700
  5. 700
  6. 4500
  7. 1600
  8. 700
  9. 1100
  10. 600
  11. 900
  12. 3000
  13. 1300
  14. 1100
  15. 500
  16. 600
  17. 1600
  18. 1000
  19. 1400
  20. 700
  21. 800
  22. 4200
  23. 9000
  24. 4000
  25. 1800
  26. 3200
  27. 800
  28. 900
  29. 1200
  30. 2700
  31. 700
  32. 1200
  33. 3500
  34. 3500
  35. 300
  36. 3000
  37. 900
  38. 1500
  39. 1000
  40. 1100

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