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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 841 · 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 3853 ÷ 42? (a) 9600 (b) 96 (c) 960
  2. 2.Best estimate of 1306 ÷ 38? (a) 33 (b) 330 (c) 3300
  3. 3.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.7 (d) 8.8
  4. 4.Best estimate of 2018 ÷ 24? (a) 10100 (b) 101 (c) 1010
  5. 5.Best estimate of 1807 ÷ 37? (a) 45 (b) 450 (c) 4500
  6. 6.Best estimate of 1388 ÷ 21? (a) 690 (b) 6900 (c) 69
  7. 7.√37 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.0 (d) 6.2
  8. 8.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  9. 9.√96 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  10. 10.√78 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  11. 11.Best estimate of 5022 ÷ 61? (a) 840 (b) 8400 (c) 84
  12. 12.Best estimate of 1971 ÷ 39? (a) 4900 (b) 490 (c) 49
  13. 13.√71 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.4
  14. 14.Best estimate of 1627 ÷ 46? (a) 33 (b) 330 (c) 3300
  15. 15.√62 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.8 (d) 7.7
  16. 16.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  17. 17.Best estimate of 4627 ÷ 66? (a) 660 (b) 6600 (c) 66
  18. 18.Best estimate of 3369 ÷ 41? (a) 840 (b) 84 (c) 8400
  19. 19.√47 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  20. 20.Best estimate of 2045 ÷ 56? (a) 34 (b) 340 (c) 3400
  21. 21.Best estimate of 1998 ÷ 72? (a) 29 (b) 2900 (c) 290
  22. 22.√86 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.4 (d) 9.3
  23. 23.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.9 (d) 9.8
  24. 24.Best estimate of 4810 ÷ 82? (a) 60 (b) 600 (c) 6000
  25. 25.√20 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.5
  26. 26.√59 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.4 (d) 7.5
  27. 27.√65 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.4
  28. 28.√52 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.2
  29. 29.Best estimate of 4474 ÷ 56? (a) 75 (b) 7500 (c) 750
  30. 30.Best estimate of 1400 ÷ 89? (a) 16 (b) 160 (c) 1600
  31. 31.√75 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 8.7
  32. 32.Best estimate of 3872 ÷ 86? (a) 43 (b) 430 (c) 4300
  33. 33.√77 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  34. 34.Best estimate of 2881 ÷ 48? (a) 5800 (b) 580 (c) 58
  35. 35.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.5 (d) 6.3
  36. 36.Best estimate of 815 ÷ 36? (a) 200 (b) 20 (c) 2000
  37. 37.√66 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  38. 38.Best estimate of 940 ÷ 24? (a) 4700 (b) 47 (c) 470
  39. 39.Best estimate of 5130 ÷ 66? (a) 73 (b) 730 (c) 7300
  40. 40.Best estimate of 2243 ÷ 38? (a) 5600 (b) 560 (c) 56

Answer key

  1. 96
  2. 33
  3. 8.9
  4. 101
  5. 45
  6. 69
  7. 6.1
  8. 5.8
  9. 9.8
  10. 8.8
  11. 84
  12. 49
  13. 8.4
  14. 33
  15. 7.9
  16. 5.1
  17. 66
  18. 84
  19. 6.9
  20. 34
  21. 29
  22. 9.3
  23. 9.7
  24. 60
  25. 4.5
  26. 7.7
  27. 8.1
  28. 7.2
  29. 75
  30. 16
  31. 8.7
  32. 43
  33. 8.8
  34. 58
  35. 6.3
  36. 20
  37. 8.1
  38. 47
  39. 73
  40. 56

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