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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 851 · 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 533 ÷ 34? (a) 18 (b) 1800 (c) 180
  2. 2.Best estimate of 634 ÷ 34? (a) 21 (b) 210 (c) 2100
  3. 3.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 10.0
  4. 4.√86 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  5. 5.√94 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.7 (d) 9.6
  6. 6.Best estimate of 5209 ÷ 79? (a) 65 (b) 6500 (c) 650
  7. 7.√89 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  8. 8.Best estimate of 2595 ÷ 63? (a) 430 (b) 43 (c) 4300
  9. 9.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  10. 10.√82 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  11. 11.√24 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  12. 12.Best estimate of 5337 ÷ 67? (a) 76 (b) 760 (c) 7600
  13. 13.Best estimate of 3324 ÷ 51? (a) 6600 (b) 660 (c) 66
  14. 14.√34 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.7 (d) 6.0
  15. 15.√67 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.1 (d) 8.2
  16. 16.Best estimate of 1101 ÷ 39? (a) 280 (b) 2800 (c) 28
  17. 17.Best estimate of 6269 ÷ 79? (a) 780 (b) 7800 (c) 78
  18. 18.Best estimate of 3253 ÷ 78? (a) 41 (b) 4100 (c) 410
  19. 19.Best estimate of 980 ÷ 48? (a) 20 (b) 2000 (c) 200
  20. 20.√53 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  21. 21.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  22. 22.√42 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  23. 23.√21 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.3
  24. 24.√71 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.1
  25. 25.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  26. 26.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  27. 27.√35 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 5.9 (d) 6.0
  28. 28.Best estimate of 6559 ÷ 79? (a) 82 (b) 8200 (c) 820
  29. 29.Best estimate of 1952 ÷ 62? (a) 3300 (b) 330 (c) 33
  30. 30.Best estimate of 6373 ÷ 84? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 5640 ÷ 69? (a) 8100 (b) 81 (c) 810
  32. 32.Best estimate of 1972 ÷ 32? (a) 66 (b) 660 (c) 6600
  33. 33.√40 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.3 (d) 6.5
  34. 34.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.8 (d) 5.9
  35. 35.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 5.2
  36. 36.Best estimate of 602 ÷ 37? (a) 1500 (b) 15 (c) 150
  37. 37.Best estimate of 3110 ÷ 79? (a) 3900 (b) 390 (c) 39
  38. 38.Best estimate of 2004 ÷ 53? (a) 400 (b) 40 (c) 4000
  39. 39.Best estimate of 7005 ÷ 76? (a) 880 (b) 8800 (c) 88
  40. 40.Best estimate of 1366 ÷ 59? (a) 230 (b) 2300 (c) 23

Answer key

  1. 18
  2. 21
  3. 9.9
  4. 9.3
  5. 9.7
  6. 65
  7. 9.4
  8. 43
  9. 6.8
  10. 9.1
  11. 4.9
  12. 76
  13. 66
  14. 5.8
  15. 8.2
  16. 28
  17. 78
  18. 41
  19. 20
  20. 7.3
  21. 7.1
  22. 6.5
  23. 4.6
  24. 8.4
  25. 7.4
  26. 7.8
  27. 5.9
  28. 82
  29. 33
  30. 80
  31. 81
  32. 66
  33. 6.3
  34. 6.1
  35. 5.1
  36. 15
  37. 39
  38. 40
  39. 88
  40. 23

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