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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 995 · 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 60 × 37? (a) 24000 (b) 2400 (c) 240
  2. 2.Best estimate of 816 + 757? (a) 1400 (b) 1800 (c) 1600
  3. 3.Best estimate of 13 × 83? (a) 800 (b) 8000 (c) 80
  4. 4.Best estimate of 56 × 13? (a) 6000 (b) 60 (c) 600
  5. 5.Best estimate of 542 + 325? (a) 600 (b) 800 (c) 1000
  6. 6.Best estimate of 57 × 66? (a) 42000 (b) 420 (c) 4200
  7. 7.Best estimate of 66 × 70? (a) 490 (b) 4900 (c) 49000
  8. 8.Best estimate of 87 × 30? (a) 2700 (b) 27000 (c) 270
  9. 9.Best estimate of 84 × 27? (a) 24000 (b) 2400 (c) 240
  10. 10.Best estimate of 72 × 29? (a) 21000 (b) 2100 (c) 210
  11. 11.Best estimate of 174 + 237? (a) 200 (b) 600 (c) 400
  12. 12.Best estimate of 585 + 231? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 164 + 549? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 295 + 130? (a) 600 (b) 200 (c) 400
  15. 15.Best estimate of 12 × 21? (a) 2000 (b) 20 (c) 200
  16. 16.Best estimate of 40 × 42? (a) 160 (b) 1600 (c) 16000
  17. 17.Best estimate of 686 + 351? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 836 + 271? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 42 × 56? (a) 240 (b) 2400 (c) 24000
  20. 20.Best estimate of 81 × 31? (a) 2400 (b) 24000 (c) 240
  21. 21.Best estimate of 436 + 334? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 73 × 18? (a) 1400 (b) 140 (c) 14000
  23. 23.Best estimate of 484 + 707? (a) 1400 (b) 1000 (c) 1200
  24. 24.Best estimate of 137 + 767? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 206 + 172? (a) 600 (b) 400 (c) 200
  26. 26.Best estimate of 123 + 779? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 321 + 311? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 43 × 77? (a) 32000 (b) 3200 (c) 320
  29. 29.Best estimate of 563 + 651? (a) 1100 (b) 1300 (c) 1500
  30. 30.Best estimate of 26 × 79? (a) 2400 (b) 240 (c) 24000
  31. 31.Best estimate of 599 + 734? (a) 1300 (b) 1100 (c) 1500
  32. 32.Best estimate of 50 × 27? (a) 150 (b) 1500 (c) 15000
  33. 33.Best estimate of 94 × 14? (a) 900 (b) 9000 (c) 90
  34. 34.Best estimate of 43 × 23? (a) 8000 (b) 80 (c) 800
  35. 35.Best estimate of 155 + 526? (a) 900 (b) 700 (c) 500
  36. 36.Best estimate of 51 × 51? (a) 2500 (b) 25000 (c) 250
  37. 37.Best estimate of 451 + 784? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 39 × 46? (a) 200 (b) 2000 (c) 20000
  39. 39.Best estimate of 79 × 96? (a) 8000 (b) 80000 (c) 800
  40. 40.Best estimate of 59 × 71? (a) 4200 (b) 420 (c) 42000

Answer key

  1. 2400
  2. 1600
  3. 800
  4. 600
  5. 800
  6. 4200
  7. 4900
  8. 2700
  9. 2400
  10. 2100
  11. 400
  12. 800
  13. 700
  14. 400
  15. 200
  16. 1600
  17. 1100
  18. 1100
  19. 2400
  20. 2400
  21. 700
  22. 1400
  23. 1200
  24. 900
  25. 400
  26. 900
  27. 600
  28. 3200
  29. 1300
  30. 2400
  31. 1300
  32. 1500
  33. 900
  34. 800
  35. 700
  36. 2500
  37. 1300
  38. 2000
  39. 8000
  40. 4200

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