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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 551 · 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.Best estimate of 5260 ÷ 57? (a) 8800 (b) 880 (c) 88
  2. 2.√84 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 9.3
  3. 3.Best estimate of 7476 ÷ 88? (a) 830 (b) 8300 (c) 83
  4. 4.Best estimate of 2902 ÷ 56? (a) 48 (b) 4800 (c) 480
  5. 5.√88 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.7
  6. 6.√52 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 7.2
  7. 7.Best estimate of 3418 ÷ 61? (a) 57 (b) 570 (c) 5700
  8. 8.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  9. 9.√41 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.4 (d) 6.5
  10. 10.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  11. 11.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 5.8
  12. 12.√27 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.4
  13. 13.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  14. 14.Best estimate of 2439 ÷ 56? (a) 4100 (b) 410 (c) 41
  15. 15.√82 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.3 (d) 9.2
  16. 16.Best estimate of 3794 ÷ 56? (a) 6300 (b) 630 (c) 63
  17. 17.Best estimate of 460 ÷ 26? (a) 150 (b) 1500 (c) 15
  18. 18.Best estimate of 2945 ÷ 51? (a) 590 (b) 5900 (c) 59
  19. 19.Best estimate of 3231 ÷ 74? (a) 4600 (b) 460 (c) 46
  20. 20.√98 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.9 (d) 9.8
  21. 21.√96 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.5
  22. 22.√59 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.9
  23. 23.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.5
  24. 24.√42 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.5 (d) 6.4
  25. 25.Best estimate of 2957 ÷ 46? (a) 59 (b) 590 (c) 5900
  26. 26.√30 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.6
  27. 27.Best estimate of 2000 ÷ 62? (a) 3300 (b) 33 (c) 330
  28. 28.√50 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.1 (d) 7.2
  29. 29.Best estimate of 2701 ÷ 37? (a) 680 (b) 6800 (c) 68
  30. 30.Best estimate of 6099 ÷ 79? (a) 7600 (b) 760 (c) 76
  31. 31.Best estimate of 1928 ÷ 29? (a) 6400 (b) 640 (c) 64
  32. 32.Best estimate of 2444 ÷ 67? (a) 3500 (b) 350 (c) 35
  33. 33.Best estimate of 7086 ÷ 76? (a) 89 (b) 890 (c) 8900
  34. 34.Best estimate of 3829 ÷ 73? (a) 5500 (b) 550 (c) 55
  35. 35.√61 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.7 (d) 7.8
  36. 36.√77 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  37. 37.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  38. 38.√67 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.2 (d) 8.0
  39. 39.Best estimate of 1028 ÷ 36? (a) 26 (b) 2600 (c) 260
  40. 40.Best estimate of 1761 ÷ 56? (a) 290 (b) 29 (c) 2900

Answer key

  1. 88
  2. 9.2
  3. 83
  4. 48
  5. 9.4
  6. 7.2
  7. 57
  8. 8.9
  9. 6.4
  10. 6.1
  11. 5.8
  12. 5.2
  13. 8.6
  14. 41
  15. 9.1
  16. 63
  17. 15
  18. 59
  19. 46
  20. 9.9
  21. 9.8
  22. 7.7
  23. 9.6
  24. 6.5
  25. 59
  26. 5.5
  27. 33
  28. 7.1
  29. 68
  30. 76
  31. 64
  32. 35
  33. 89
  34. 55
  35. 7.8
  36. 8.8
  37. 4.6
  38. 8.2
  39. 26
  40. 29

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