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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 135 · 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.√94 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  2. 2.Best estimate of 703 ÷ 39? (a) 180 (b) 1800 (c) 18
  3. 3.√34 to 1 decimal place? (a) 5.6 (b) 5.9 (c) 5.7 (d) 5.8
  4. 4.Best estimate of 1219 ÷ 53? (a) 24 (b) 2400 (c) 240
  5. 5.√45 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  6. 6.Best estimate of 3752 ÷ 53? (a) 75 (b) 750 (c) 7500
  7. 7.√59 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.7 (d) 7.6
  8. 8.Best estimate of 2596 ÷ 79? (a) 320 (b) 32 (c) 3200
  9. 9.Best estimate of 1519 ÷ 72? (a) 22 (b) 2200 (c) 220
  10. 10.Best estimate of 2365 ÷ 33? (a) 790 (b) 7900 (c) 79
  11. 11.Best estimate of 5717 ÷ 73? (a) 82 (b) 8200 (c) 820
  12. 12.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.9 (d) 8.8
  13. 13.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8
  14. 14.√78 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  15. 15.Best estimate of 6707 ÷ 88? (a) 75 (b) 750 (c) 7500
  16. 16.√56 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.2
  17. 17.Best estimate of 2274 ÷ 27? (a) 76 (b) 760 (c) 7600
  18. 18.√88 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.4
  19. 19.√47 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.0 (d) 7.2
  20. 20.Best estimate of 625 ÷ 31? (a) 210 (b) 2100 (c) 21
  21. 21.Best estimate of 1085 ÷ 31? (a) 3600 (b) 36 (c) 360
  22. 22.Best estimate of 5805 ÷ 64? (a) 97 (b) 970 (c) 9700
  23. 23.√70 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.3 (d) 8.5
  24. 24.Best estimate of 2014 ÷ 48? (a) 40 (b) 400 (c) 4000
  25. 25.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.0 (d) 6.1
  26. 26.Best estimate of 4481 ÷ 56? (a) 7500 (b) 750 (c) 75
  27. 27.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 4.9
  28. 28.Best estimate of 3659 ÷ 47? (a) 73 (b) 7300 (c) 730
  29. 29.Best estimate of 2832 ÷ 37? (a) 710 (b) 71 (c) 7100
  30. 30.√66 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.3 (d) 8.2
  31. 31.Best estimate of 2632 ÷ 29? (a) 8800 (b) 88 (c) 880
  32. 32.√76 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  33. 33.√86 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  34. 34.Best estimate of 902 ÷ 33? (a) 30 (b) 300 (c) 3000
  35. 35.√75 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.9 (d) 8.8
  36. 36.Best estimate of 2132 ÷ 62? (a) 36 (b) 360 (c) 3600
  37. 37.Best estimate of 4263 ÷ 58? (a) 710 (b) 71 (c) 7100
  38. 38.Best estimate of 4343 ÷ 48? (a) 8700 (b) 870 (c) 87
  39. 39.Best estimate of 1762 ÷ 24? (a) 88 (b) 8800 (c) 880
  40. 40.Best estimate of 5816 ÷ 68? (a) 830 (b) 83 (c) 8300

Answer key

  1. 9.7
  2. 18
  3. 5.8
  4. 24
  5. 6.7
  6. 75
  7. 7.7
  8. 32
  9. 22
  10. 79
  11. 82
  12. 8.8
  13. 9.9
  14. 8.8
  15. 75
  16. 7.5
  17. 76
  18. 9.4
  19. 6.9
  20. 21
  21. 36
  22. 97
  23. 8.4
  24. 40
  25. 6.1
  26. 75
  27. 5.1
  28. 73
  29. 71
  30. 8.1
  31. 88
  32. 8.7
  33. 9.3
  34. 30
  35. 8.7
  36. 36
  37. 71
  38. 87
  39. 88
  40. 83

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