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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 15 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.√38 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 5.9
  2. 2.√75 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  3. 3.√62 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 7.9
  4. 4.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  5. 5.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  6. 6.√94 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.8 (d) 9.7
  7. 7.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.5
  8. 8.Best estimate of 2952 ÷ 77? (a) 370 (b) 3700 (c) 37
  9. 9.√74 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.7 (d) 8.6
  10. 10.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  11. 11.Best estimate of 4813 ÷ 77? (a) 600 (b) 60 (c) 6000
  12. 12.√52 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.2 (d) 7.1
  13. 13.√31 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 5.6
  14. 14.Best estimate of 2044 ÷ 28? (a) 6800 (b) 680 (c) 68
  15. 15.Best estimate of 1933 ÷ 23? (a) 970 (b) 9700 (c) 97
  16. 16.Best estimate of 1196 ÷ 34? (a) 400 (b) 4000 (c) 40
  17. 17.Best estimate of 1700 ÷ 69? (a) 2400 (b) 24 (c) 240
  18. 18.Best estimate of 3240 ÷ 34? (a) 108 (b) 10800 (c) 1080
  19. 19.Best estimate of 2884 ÷ 37? (a) 7200 (b) 72 (c) 720
  20. 20.Best estimate of 4333 ÷ 74? (a) 62 (b) 620 (c) 6200
  21. 21.Best estimate of 1664 ÷ 57? (a) 28 (b) 280 (c) 2800
  22. 22.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 10.1 (d) 9.9
  23. 23.Best estimate of 3460 ÷ 69? (a) 49 (b) 4900 (c) 490
  24. 24.Best estimate of 4868 ÷ 82? (a) 610 (b) 61 (c) 6100
  25. 25.Best estimate of 2562 ÷ 36? (a) 64 (b) 6400 (c) 640
  26. 26.√53 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  27. 27.Best estimate of 475 ÷ 36? (a) 1200 (b) 12 (c) 120
  28. 28.Best estimate of 5227 ÷ 81? (a) 65 (b) 6500 (c) 650
  29. 29.Best estimate of 1136 ÷ 74? (a) 16 (b) 1600 (c) 160
  30. 30.Best estimate of 3569 ÷ 63? (a) 590 (b) 5900 (c) 59
  31. 31.Best estimate of 1294 ÷ 38? (a) 320 (b) 3200 (c) 32
  32. 32.Best estimate of 8135 ÷ 87? (a) 900 (b) 9000 (c) 90
  33. 33.√63 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 8.0 (d) 7.9
  34. 34.Best estimate of 4252 ÷ 82? (a) 5300 (b) 530 (c) 53
  35. 35.√32 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.4
  36. 36.Best estimate of 4519 ÷ 49? (a) 900 (b) 9000 (c) 90
  37. 37.Best estimate of 3633 ÷ 54? (a) 7300 (b) 730 (c) 73
  38. 38.Best estimate of 6733 ÷ 86? (a) 7500 (b) 750 (c) 75
  39. 39.Best estimate of 6279 ÷ 79? (a) 7800 (b) 780 (c) 78
  40. 40.Best estimate of 3539 ÷ 72? (a) 510 (b) 51 (c) 5100

Answer key

  1. 6.2
  2. 8.7
  3. 7.9
  4. 4.8
  5. 6.6
  6. 9.7
  7. 7.4
  8. 37
  9. 8.6
  10. 4.9
  11. 60
  12. 7.2
  13. 5.6
  14. 68
  15. 97
  16. 40
  17. 24
  18. 108
  19. 72
  20. 62
  21. 28
  22. 9.9
  23. 49
  24. 61
  25. 64
  26. 7.3
  27. 12
  28. 65
  29. 16
  30. 59
  31. 32
  32. 90
  33. 7.9
  34. 53
  35. 5.7
  36. 90
  37. 73
  38. 75
  39. 78
  40. 51

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