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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 807 · 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 2734 ÷ 54? (a) 550 (b) 5500 (c) 55
  2. 2.√42 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.4 (d) 6.3
  3. 3.Best estimate of 6013 ÷ 81? (a) 7500 (b) 750 (c) 75
  4. 4.Best estimate of 4601 ÷ 61? (a) 7700 (b) 77 (c) 770
  5. 5.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.8 (d) 8.7
  6. 6.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.7 (d) 8.8
  7. 7.√51 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.1
  8. 8.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.1
  9. 9.Best estimate of 2414 ÷ 32? (a) 800 (b) 80 (c) 8000
  10. 10.Best estimate of 1405 ÷ 52? (a) 28 (b) 280 (c) 2800
  11. 11.Best estimate of 4825 ÷ 83? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 1990 ÷ 24? (a) 1000 (b) 100 (c) 10000
  13. 13.Best estimate of 5031 ÷ 64? (a) 8400 (b) 840 (c) 84
  14. 14.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.6
  15. 15.Best estimate of 5598 ÷ 62? (a) 93 (b) 9300 (c) 930
  16. 16.√20 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.5
  17. 17.Best estimate of 1698 ÷ 61? (a) 280 (b) 2800 (c) 28
  18. 18.Best estimate of 2545 ÷ 43? (a) 6400 (b) 640 (c) 64
  19. 19.√87 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  20. 20.Best estimate of 4523 ÷ 88? (a) 500 (b) 50 (c) 5000
  21. 21.Best estimate of 3906 ÷ 57? (a) 65 (b) 6500 (c) 650
  22. 22.√84 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.2 (d) 9.4
  23. 23.Best estimate of 2931 ÷ 36? (a) 7300 (b) 730 (c) 73
  24. 24.Best estimate of 2699 ÷ 42? (a) 67 (b) 670 (c) 6700
  25. 25.√24 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.9
  26. 26.√75 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  27. 27.Best estimate of 5284 ÷ 72? (a) 7500 (b) 75 (c) 750
  28. 28.Best estimate of 6639 ÷ 74? (a) 9500 (b) 950 (c) 95
  29. 29.Best estimate of 926 ÷ 29? (a) 3100 (b) 310 (c) 31
  30. 30.Best estimate of 1964 ÷ 36? (a) 4900 (b) 49 (c) 490
  31. 31.Best estimate of 2097 ÷ 24? (a) 10500 (b) 105 (c) 1050
  32. 32.Best estimate of 863 ÷ 38? (a) 2200 (b) 220 (c) 22
  33. 33.Best estimate of 2315 ÷ 58? (a) 3900 (b) 390 (c) 39
  34. 34.Best estimate of 667 ÷ 29? (a) 2200 (b) 22 (c) 220
  35. 35.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  36. 36.Best estimate of 5649 ÷ 72? (a) 8100 (b) 81 (c) 810
  37. 37.Best estimate of 2146 ÷ 61? (a) 36 (b) 360 (c) 3600
  38. 38.Best estimate of 2007 ÷ 46? (a) 4000 (b) 40 (c) 400
  39. 39.Best estimate of 1979 ÷ 86? (a) 220 (b) 2200 (c) 22
  40. 40.Best estimate of 1291 ÷ 69? (a) 1800 (b) 180 (c) 18

Answer key

  1. 55
  2. 6.5
  3. 75
  4. 77
  5. 8.6
  6. 8.9
  7. 7.1
  8. 8.3
  9. 80
  10. 28
  11. 60
  12. 100
  13. 84
  14. 7.4
  15. 93
  16. 4.5
  17. 28
  18. 64
  19. 9.3
  20. 50
  21. 65
  22. 9.2
  23. 73
  24. 67
  25. 4.9
  26. 8.7
  27. 75
  28. 95
  29. 31
  30. 49
  31. 105
  32. 22
  33. 39
  34. 22
  35. 8.9
  36. 81
  37. 36
  38. 40
  39. 22
  40. 18

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