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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 855 · 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 40 × 53? (a) 20000 (b) 2000 (c) 200
  2. 2.Best estimate of 74 × 79? (a) 56000 (b) 5600 (c) 560
  3. 3.Best estimate of 302 + 600? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 198 + 640? (a) 1000 (b) 800 (c) 600
  5. 5.Best estimate of 311 + 861? (a) 1200 (b) 1000 (c) 1400
  6. 6.Best estimate of 308 + 390? (a) 500 (b) 700 (c) 900
  7. 7.Best estimate of 80 × 14? (a) 80 (b) 800 (c) 8000
  8. 8.Best estimate of 260 + 524? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 620 + 676? (a) 1300 (b) 1500 (c) 1100
  10. 10.Best estimate of 225 + 339? (a) 500 (b) 700 (c) 300
  11. 11.Best estimate of 80 × 43? (a) 3200 (b) 320 (c) 32000
  12. 12.Best estimate of 277 + 164? (a) 300 (b) 500 (c) 700
  13. 13.Best estimate of 415 + 651? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 537 + 534? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 411 + 565? (a) 800 (b) 1000 (c) 1200
  16. 16.Best estimate of 19 × 14? (a) 20 (b) 2000 (c) 200
  17. 17.Best estimate of 841 + 538? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 61 × 26? (a) 1800 (b) 180 (c) 18000
  19. 19.Best estimate of 78 × 13? (a) 800 (b) 8000 (c) 80
  20. 20.Best estimate of 56 × 49? (a) 30000 (b) 300 (c) 3000
  21. 21.Best estimate of 295 + 836? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 56 × 47? (a) 30000 (b) 3000 (c) 300
  23. 23.Best estimate of 73 × 64? (a) 4200 (b) 42000 (c) 420
  24. 24.Best estimate of 140 + 769? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 444 + 666? (a) 900 (b) 1100 (c) 1300
  26. 26.Best estimate of 34 × 46? (a) 150 (b) 15000 (c) 1500
  27. 27.Best estimate of 196 + 779? (a) 1000 (b) 1200 (c) 800
  28. 28.Best estimate of 425 + 515? (a) 1100 (b) 700 (c) 900
  29. 29.Best estimate of 519 + 465? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 837 + 339? (a) 1300 (b) 1100 (c) 900
  31. 31.Best estimate of 592 + 775? (a) 1200 (b) 1600 (c) 1400
  32. 32.Best estimate of 28 × 52? (a) 15000 (b) 1500 (c) 150
  33. 33.Best estimate of 36 × 39? (a) 1600 (b) 16000 (c) 160
  34. 34.Best estimate of 811 + 131? (a) 900 (b) 700 (c) 1100
  35. 35.Best estimate of 231 + 729? (a) 700 (b) 1100 (c) 900
  36. 36.Best estimate of 72 × 26? (a) 210 (b) 21000 (c) 2100
  37. 37.Best estimate of 88 × 76? (a) 720 (b) 7200 (c) 72000
  38. 38.Best estimate of 83 × 56? (a) 4800 (b) 48000 (c) 480
  39. 39.Best estimate of 142 + 357? (a) 300 (b) 500 (c) 700
  40. 40.Best estimate of 580 + 253? (a) 1100 (b) 700 (c) 900

Answer key

  1. 2000
  2. 5600
  3. 900
  4. 800
  5. 1200
  6. 700
  7. 800
  8. 800
  9. 1300
  10. 500
  11. 3200
  12. 500
  13. 1100
  14. 1000
  15. 1000
  16. 200
  17. 1300
  18. 1800
  19. 800
  20. 3000
  21. 1100
  22. 3000
  23. 4200
  24. 900
  25. 1100
  26. 1500
  27. 1000
  28. 900
  29. 1000
  30. 1100
  31. 1400
  32. 1500
  33. 1600
  34. 900
  35. 900
  36. 2100
  37. 7200
  38. 4800
  39. 500
  40. 900

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