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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 658 · 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 26 × 50? (a) 15000 (b) 1500 (c) 150
  2. 2.Best estimate of 17 × 97? (a) 2000 (b) 20000 (c) 200
  3. 3.Best estimate of 647 + 413? (a) 1200 (b) 800 (c) 1000
  4. 4.Best estimate of 262 + 662? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 13 × 84? (a) 800 (b) 8000 (c) 80
  6. 6.Best estimate of 54 × 12? (a) 5000 (b) 50 (c) 500
  7. 7.Best estimate of 80 × 24? (a) 1600 (b) 160 (c) 16000
  8. 8.Best estimate of 730 + 626? (a) 1500 (b) 1300 (c) 1100
  9. 9.Best estimate of 62 × 48? (a) 30000 (b) 300 (c) 3000
  10. 10.Best estimate of 37 × 47? (a) 20000 (b) 2000 (c) 200
  11. 11.Best estimate of 92 × 68? (a) 630 (b) 63000 (c) 6300
  12. 12.Best estimate of 49 × 44? (a) 20000 (b) 200 (c) 2000
  13. 13.Best estimate of 751 + 342? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 778 + 536? (a) 1100 (b) 1300 (c) 1500
  15. 15.Best estimate of 92 × 86? (a) 810 (b) 81000 (c) 8100
  16. 16.Best estimate of 86 × 46? (a) 4500 (b) 45000 (c) 450
  17. 17.Best estimate of 224 + 536? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 570 + 313? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 56 × 70? (a) 4200 (b) 420 (c) 42000
  20. 20.Best estimate of 337 + 626? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 331 + 754? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 751 + 701? (a) 1300 (b) 1700 (c) 1500
  23. 23.Best estimate of 82 × 33? (a) 2400 (b) 24000 (c) 240
  24. 24.Best estimate of 73 × 63? (a) 4200 (b) 42000 (c) 420
  25. 25.Best estimate of 50 × 19? (a) 100 (b) 1000 (c) 10000
  26. 26.Best estimate of 603 + 306? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 37 × 38? (a) 1600 (b) 160 (c) 16000
  28. 28.Best estimate of 649 + 187? (a) 1000 (b) 800 (c) 600
  29. 29.Best estimate of 285 + 838? (a) 1100 (b) 900 (c) 1300
  30. 30.Best estimate of 16 × 14? (a) 200 (b) 2000 (c) 20
  31. 31.Best estimate of 831 + 279? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 752 + 554? (a) 1600 (b) 1400 (c) 1200
  33. 33.Best estimate of 53 × 71? (a) 3500 (b) 350 (c) 35000
  34. 34.Best estimate of 524 + 352? (a) 1100 (b) 900 (c) 700
  35. 35.Best estimate of 201 + 267? (a) 700 (b) 500 (c) 300
  36. 36.Best estimate of 661 + 694? (a) 1200 (b) 1400 (c) 1600
  37. 37.Best estimate of 29 × 30? (a) 900 (b) 90 (c) 9000
  38. 38.Best estimate of 46 × 51? (a) 2500 (b) 25000 (c) 250
  39. 39.Best estimate of 49 × 43? (a) 200 (b) 2000 (c) 20000
  40. 40.Best estimate of 24 × 14? (a) 200 (b) 2000 (c) 20

Answer key

  1. 1500
  2. 2000
  3. 1000
  4. 1000
  5. 800
  6. 500
  7. 1600
  8. 1300
  9. 3000
  10. 2000
  11. 6300
  12. 2000
  13. 1100
  14. 1300
  15. 8100
  16. 4500
  17. 700
  18. 900
  19. 4200
  20. 900
  21. 1100
  22. 1500
  23. 2400
  24. 4200
  25. 1000
  26. 900
  27. 1600
  28. 800
  29. 1100
  30. 200
  31. 1100
  32. 1400
  33. 3500
  34. 900
  35. 500
  36. 1400
  37. 900
  38. 2500
  39. 2000
  40. 200

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