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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 509 · 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 × 16? (a) 16000 (b) 1600 (c) 160
  2. 2.Best estimate of 466 + 233? (a) 500 (b) 700 (c) 900
  3. 3.Best estimate of 56 × 54? (a) 300 (b) 3000 (c) 30000
  4. 4.Best estimate of 16 × 12? (a) 2000 (b) 20 (c) 200
  5. 5.Best estimate of 46 × 26? (a) 150 (b) 15000 (c) 1500
  6. 6.Best estimate of 18 × 28? (a) 6000 (b) 600 (c) 60
  7. 7.Best estimate of 417 + 594? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 292 + 280? (a) 600 (b) 400 (c) 800
  9. 9.Best estimate of 351 + 611? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 369 + 161? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 134 + 149? (a) 200 (b) 0 (c) 400
  12. 12.Best estimate of 32 × 54? (a) 15000 (b) 150 (c) 1500
  13. 13.Best estimate of 736 + 314? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 87 × 89? (a) 810 (b) 8100 (c) 81000
  15. 15.Best estimate of 36 × 91? (a) 3600 (b) 360 (c) 36000
  16. 16.Best estimate of 423 + 551? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 63 × 23? (a) 1200 (b) 12000 (c) 120
  18. 18.Best estimate of 77 × 80? (a) 64000 (b) 6400 (c) 640
  19. 19.Best estimate of 31 × 70? (a) 210 (b) 2100 (c) 21000
  20. 20.Best estimate of 277 + 327? (a) 400 (b) 800 (c) 600
  21. 21.Best estimate of 266 + 123? (a) 400 (b) 200 (c) 600
  22. 22.Best estimate of 617 + 632? (a) 1400 (b) 1000 (c) 1200
  23. 23.Best estimate of 263 + 617? (a) 1100 (b) 700 (c) 900
  24. 24.Best estimate of 23 × 76? (a) 16000 (b) 1600 (c) 160
  25. 25.Best estimate of 174 + 769? (a) 1000 (b) 1200 (c) 800
  26. 26.Best estimate of 69 × 82? (a) 5600 (b) 56000 (c) 560
  27. 27.Best estimate of 137 + 631? (a) 900 (b) 700 (c) 500
  28. 28.Best estimate of 467 + 596? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 661 + 793? (a) 1500 (b) 1700 (c) 1300
  30. 30.Best estimate of 486 + 196? (a) 700 (b) 500 (c) 900
  31. 31.Best estimate of 26 × 90? (a) 27000 (b) 2700 (c) 270
  32. 32.Best estimate of 38 × 42? (a) 160 (b) 1600 (c) 16000
  33. 33.Best estimate of 59 × 77? (a) 480 (b) 48000 (c) 4800
  34. 34.Best estimate of 251 + 265? (a) 400 (b) 800 (c) 600
  35. 35.Best estimate of 176 + 262? (a) 300 (b) 700 (c) 500
  36. 36.Best estimate of 776 + 351? (a) 1000 (b) 1200 (c) 1400
  37. 37.Best estimate of 76 × 77? (a) 6400 (b) 64000 (c) 640
  38. 38.Best estimate of 193 + 790? (a) 800 (b) 1200 (c) 1000
  39. 39.Best estimate of 21 × 36? (a) 800 (b) 80 (c) 8000
  40. 40.Best estimate of 264 + 231? (a) 700 (b) 500 (c) 300

Answer key

  1. 1600
  2. 700
  3. 3000
  4. 200
  5. 1500
  6. 600
  7. 1000
  8. 600
  9. 1000
  10. 600
  11. 200
  12. 1500
  13. 1000
  14. 8100
  15. 3600
  16. 1000
  17. 1200
  18. 6400
  19. 2100
  20. 600
  21. 400
  22. 1200
  23. 900
  24. 1600
  25. 1000
  26. 5600
  27. 700
  28. 1100
  29. 1500
  30. 700
  31. 2700
  32. 1600
  33. 4800
  34. 600
  35. 500
  36. 1200
  37. 6400
  38. 1000
  39. 800
  40. 500

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