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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 259 · 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 633 + 545? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 97 × 26? (a) 300 (b) 3000 (c) 30000
  3. 3.Best estimate of 33 × 66? (a) 21000 (b) 210 (c) 2100
  4. 4.Best estimate of 626 + 389? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 59 × 51? (a) 300 (b) 3000 (c) 30000
  6. 6.Best estimate of 659 + 147? (a) 1000 (b) 600 (c) 800
  7. 7.Best estimate of 36 × 36? (a) 1600 (b) 160 (c) 16000
  8. 8.Best estimate of 811 + 532? (a) 1100 (b) 1500 (c) 1300
  9. 9.Best estimate of 26 × 12? (a) 3000 (b) 300 (c) 30
  10. 10.Best estimate of 581 + 655? (a) 1500 (b) 1100 (c) 1300
  11. 11.Best estimate of 463 + 136? (a) 800 (b) 400 (c) 600
  12. 12.Best estimate of 318 + 193? (a) 700 (b) 300 (c) 500
  13. 13.Best estimate of 41 × 96? (a) 400 (b) 4000 (c) 40000
  14. 14.Best estimate of 538 + 665? (a) 1000 (b) 1400 (c) 1200
  15. 15.Best estimate of 751 + 571? (a) 1400 (b) 1600 (c) 1200
  16. 16.Best estimate of 32 × 13? (a) 300 (b) 30 (c) 3000
  17. 17.Best estimate of 91 × 23? (a) 180 (b) 18000 (c) 1800
  18. 18.Best estimate of 214 + 684? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 30 × 13? (a) 3000 (b) 300 (c) 30
  20. 20.Best estimate of 765 + 256? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 390 + 720? (a) 900 (b) 1100 (c) 1300
  22. 22.Best estimate of 425 + 314? (a) 700 (b) 900 (c) 500
  23. 23.Best estimate of 257 + 349? (a) 800 (b) 400 (c) 600
  24. 24.Best estimate of 22 × 43? (a) 8000 (b) 800 (c) 80
  25. 25.Best estimate of 417 + 206? (a) 400 (b) 600 (c) 800
  26. 26.Best estimate of 129 + 259? (a) 200 (b) 400 (c) 600
  27. 27.Best estimate of 222 + 309? (a) 500 (b) 700 (c) 300
  28. 28.Best estimate of 69 × 27? (a) 21000 (b) 2100 (c) 210
  29. 29.Best estimate of 776 + 122? (a) 700 (b) 900 (c) 1100
  30. 30.Best estimate of 52 × 73? (a) 350 (b) 35000 (c) 3500
  31. 31.Best estimate of 335 + 847? (a) 1300 (b) 1100 (c) 900
  32. 32.Best estimate of 565 + 248? (a) 1000 (b) 800 (c) 600
  33. 33.Best estimate of 18 × 26? (a) 60 (b) 6000 (c) 600
  34. 34.Best estimate of 96 × 83? (a) 8000 (b) 800 (c) 80000
  35. 35.Best estimate of 56 × 62? (a) 3600 (b) 36000 (c) 360
  36. 36.Best estimate of 74 × 38? (a) 2800 (b) 28000 (c) 280
  37. 37.Best estimate of 69 × 51? (a) 350 (b) 3500 (c) 35000
  38. 38.Best estimate of 131 + 752? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 720 + 639? (a) 1300 (b) 1500 (c) 1100
  40. 40.Best estimate of 232 + 316? (a) 300 (b) 700 (c) 500

Answer key

  1. 1100
  2. 3000
  3. 2100
  4. 1000
  5. 3000
  6. 800
  7. 1600
  8. 1300
  9. 300
  10. 1300
  11. 600
  12. 500
  13. 4000
  14. 1200
  15. 1400
  16. 300
  17. 1800
  18. 900
  19. 300
  20. 1100
  21. 1100
  22. 700
  23. 600
  24. 800
  25. 600
  26. 400
  27. 500
  28. 2100
  29. 900
  30. 3500
  31. 1100
  32. 800
  33. 600
  34. 8000
  35. 3600
  36. 2800
  37. 3500
  38. 900
  39. 1300
  40. 500

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