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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 487 · 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.√71 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.4
  2. 2.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  3. 3.Best estimate of 2627 ÷ 36? (a) 66 (b) 660 (c) 6600
  4. 4.Best estimate of 2389 ÷ 36? (a) 600 (b) 60 (c) 6000
  5. 5.Best estimate of 3925 ÷ 57? (a) 650 (b) 65 (c) 6500
  6. 6.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 10.1 (d) 9.9
  7. 7.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  8. 8.√41 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.4
  9. 9.Best estimate of 842 ÷ 32? (a) 28 (b) 280 (c) 2800
  10. 10.Best estimate of 3925 ÷ 51? (a) 7900 (b) 79 (c) 790
  11. 11.Best estimate of 4963 ÷ 57? (a) 83 (b) 830 (c) 8300
  12. 12.√26 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.1
  13. 13.√46 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.6 (d) 6.8
  14. 14.Best estimate of 1925 ÷ 36? (a) 480 (b) 4800 (c) 48
  15. 15.Best estimate of 541 ÷ 34? (a) 1800 (b) 180 (c) 18
  16. 16.Best estimate of 2494 ÷ 84? (a) 310 (b) 31 (c) 3100
  17. 17.Best estimate of 4119 ÷ 59? (a) 6900 (b) 69 (c) 690
  18. 18.√37 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 6.1
  19. 19.Best estimate of 549 ÷ 23? (a) 270 (b) 2700 (c) 27
  20. 20.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  21. 21.Best estimate of 2815 ÷ 81? (a) 35 (b) 3500 (c) 350
  22. 22.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  23. 23.Best estimate of 2084 ÷ 71? (a) 30 (b) 300 (c) 3000
  24. 24.Best estimate of 2411 ÷ 88? (a) 270 (b) 2700 (c) 27
  25. 25.√98 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 10.2 (d) 10.1
  26. 26.Best estimate of 1085 ÷ 22? (a) 54 (b) 540 (c) 5400
  27. 27.√61 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  28. 28.√21 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.4 (d) 4.6
  29. 29.Best estimate of 981 ÷ 32? (a) 33 (b) 330 (c) 3300
  30. 30.Best estimate of 1755 ÷ 44? (a) 440 (b) 4400 (c) 44
  31. 31.Best estimate of 2958 ÷ 33? (a) 990 (b) 99 (c) 9900
  32. 32.Best estimate of 1583 ÷ 56? (a) 26 (b) 260 (c) 2600
  33. 33.√43 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7
  34. 34.Best estimate of 2411 ÷ 34? (a) 800 (b) 80 (c) 8000
  35. 35.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  36. 36.√24 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.9
  37. 37.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 8.1
  38. 38.√86 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  39. 39.√78 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  40. 40.Best estimate of 2059 ÷ 42? (a) 5100 (b) 510 (c) 51

Answer key

  1. 8.4
  2. 8.1
  3. 66
  4. 60
  5. 65
  6. 9.8
  7. 9.1
  8. 6.4
  9. 28
  10. 79
  11. 83
  12. 5.1
  13. 6.8
  14. 48
  15. 18
  16. 31
  17. 69
  18. 6.1
  19. 27
  20. 9.4
  21. 35
  22. 5.8
  23. 30
  24. 27
  25. 9.9
  26. 54
  27. 7.8
  28. 4.6
  29. 33
  30. 44
  31. 99
  32. 26
  33. 6.6
  34. 80
  35. 9.7
  36. 4.9
  37. 7.9
  38. 9.3
  39. 8.8
  40. 51

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