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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 360 · 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 935 ÷ 42? (a) 230 (b) 23 (c) 2300
  2. 2.Best estimate of 1430 ÷ 24? (a) 7200 (b) 72 (c) 720
  3. 3.Best estimate of 1598 ÷ 24? (a) 8000 (b) 80 (c) 800
  4. 4.Best estimate of 2020 ÷ 72? (a) 2900 (b) 29 (c) 290
  5. 5.Best estimate of 3750 ÷ 82? (a) 47 (b) 4700 (c) 470
  6. 6.Best estimate of 2891 ÷ 58? (a) 48 (b) 4800 (c) 480
  7. 7.Best estimate of 1328 ÷ 23? (a) 66 (b) 660 (c) 6600
  8. 8.Best estimate of 1875 ÷ 36? (a) 470 (b) 47 (c) 4700
  9. 9.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 7.3
  10. 10.√96 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  11. 11.Best estimate of 934 ÷ 46? (a) 190 (b) 19 (c) 1900
  12. 12.√88 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.3
  13. 13.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  14. 14.Best estimate of 5220 ÷ 74? (a) 750 (b) 7500 (c) 75
  15. 15.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  16. 16.√38 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.1 (d) 6.2
  17. 17.Best estimate of 1814 ÷ 26? (a) 600 (b) 60 (c) 6000
  18. 18.Best estimate of 5013 ÷ 58? (a) 8400 (b) 840 (c) 84
  19. 19.Best estimate of 2993 ÷ 42? (a) 7500 (b) 75 (c) 750
  20. 20.Best estimate of 2440 ÷ 86? (a) 27 (b) 2700 (c) 270
  21. 21.Best estimate of 1105 ÷ 32? (a) 37 (b) 3700 (c) 370
  22. 22.Best estimate of 563 ÷ 22? (a) 280 (b) 2800 (c) 28
  23. 23.Best estimate of 7686 ÷ 82? (a) 960 (b) 96 (c) 9600
  24. 24.Best estimate of 2221 ÷ 38? (a) 560 (b) 56 (c) 5600
  25. 25.Best estimate of 3771 ÷ 53? (a) 750 (b) 7500 (c) 75
  26. 26.Best estimate of 4825 ÷ 59? (a) 8000 (b) 800 (c) 80
  27. 27.√84 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.0
  28. 28.√22 to 1 decimal place? (a) 5.0 (b) 4.7 (c) 4.8 (d) 4.9
  29. 29.√30 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.2
  30. 30.Best estimate of 3690 ÷ 77? (a) 460 (b) 4600 (c) 46
  31. 31.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.3 (d) 6.2
  32. 32.Best estimate of 1641 ÷ 86? (a) 1800 (b) 18 (c) 180
  33. 33.√78 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.9
  34. 34.Best estimate of 2356 ÷ 82? (a) 2900 (b) 29 (c) 290
  35. 35.Best estimate of 1023 ÷ 47? (a) 2000 (b) 20 (c) 200
  36. 36.Best estimate of 3753 ÷ 57? (a) 63 (b) 6300 (c) 630
  37. 37.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.3
  38. 38.√41 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.7
  39. 39.Best estimate of 525 ÷ 42? (a) 130 (b) 1300 (c) 13
  40. 40.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.0

Answer key

  1. 23
  2. 72
  3. 80
  4. 29
  5. 47
  6. 48
  7. 66
  8. 47
  9. 7.1
  10. 9.8
  11. 19
  12. 9.4
  13. 4.9
  14. 75
  15. 4.6
  16. 6.2
  17. 60
  18. 84
  19. 75
  20. 27
  21. 37
  22. 28
  23. 96
  24. 56
  25. 75
  26. 80
  27. 9.2
  28. 4.7
  29. 5.5
  30. 46
  31. 6.1
  32. 18
  33. 8.8
  34. 29
  35. 20
  36. 63
  37. 4.5
  38. 6.4
  39. 13
  40. 6.3

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