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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 859 · 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.√66 to 1 decimal place? (a) 7.9 (b) 8.2 (c) 8.1 (d) 8.0
  2. 2.Best estimate of 1431 ÷ 23? (a) 7200 (b) 720 (c) 72
  3. 3.Best estimate of 2459 ÷ 34? (a) 82 (b) 820 (c) 8200
  4. 4.Best estimate of 1738 ÷ 88? (a) 1900 (b) 19 (c) 190
  5. 5.√45 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  6. 6.Best estimate of 2680 ÷ 37? (a) 67 (b) 670 (c) 6700
  7. 7.Best estimate of 5899 ÷ 73? (a) 840 (b) 8400 (c) 84
  8. 8.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.5 (d) 5.2
  9. 9.Best estimate of 7098 ÷ 89? (a) 790 (b) 79 (c) 7900
  10. 10.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.4 (d) 6.3
  11. 11.Best estimate of 4953 ÷ 54? (a) 990 (b) 9900 (c) 99
  12. 12.Best estimate of 5295 ÷ 69? (a) 760 (b) 76 (c) 7600
  13. 13.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 5.1
  14. 14.√30 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  15. 15.Best estimate of 1276 ÷ 52? (a) 260 (b) 26 (c) 2600
  16. 16.Best estimate of 4966 ÷ 68? (a) 7100 (b) 710 (c) 71
  17. 17.Best estimate of 269 ÷ 21? (a) 13 (b) 1300 (c) 130
  18. 18.Best estimate of 3297 ÷ 47? (a) 660 (b) 6600 (c) 66
  19. 19.Best estimate of 3319 ÷ 87? (a) 370 (b) 3700 (c) 37
  20. 20.√62 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 8.2
  21. 21.√43 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 6.6
  22. 22.Best estimate of 2224 ÷ 38? (a) 5600 (b) 56 (c) 560
  23. 23.Best estimate of 667 ÷ 34? (a) 220 (b) 2200 (c) 22
  24. 24.√47 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  25. 25.Best estimate of 602 ÷ 29? (a) 20 (b) 2000 (c) 200
  26. 26.√82 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  27. 27.Best estimate of 6488 ÷ 79? (a) 8100 (b) 810 (c) 81
  28. 28.√48 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.7 (d) 6.8
  29. 29.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  30. 30.Best estimate of 4064 ÷ 53? (a) 810 (b) 8100 (c) 81
  31. 31.Best estimate of 398 ÷ 26? (a) 13 (b) 130 (c) 1300
  32. 32.√29 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.6 (d) 5.4
  33. 33.Best estimate of 1454 ÷ 21? (a) 73 (b) 730 (c) 7300
  34. 34.Best estimate of 1065 ÷ 62? (a) 1800 (b) 180 (c) 18
  35. 35.√34 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.8 (d) 5.7
  36. 36.Best estimate of 599 ÷ 47? (a) 1200 (b) 120 (c) 12
  37. 37.Best estimate of 6447 ÷ 77? (a) 81 (b) 810 (c) 8100
  38. 38.Best estimate of 1920 ÷ 23? (a) 9600 (b) 960 (c) 96
  39. 39.Best estimate of 4731 ÷ 62? (a) 790 (b) 79 (c) 7900
  40. 40.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5

Answer key

  1. 8.1
  2. 72
  3. 82
  4. 19
  5. 6.7
  6. 67
  7. 84
  8. 5.3
  9. 79
  10. 6.1
  11. 99
  12. 76
  13. 4.9
  14. 5.5
  15. 26
  16. 71
  17. 13
  18. 66
  19. 37
  20. 7.9
  21. 6.6
  22. 56
  23. 22
  24. 6.9
  25. 20
  26. 9.1
  27. 81
  28. 6.9
  29. 9.7
  30. 81
  31. 13
  32. 5.4
  33. 73
  34. 18
  35. 5.8
  36. 12
  37. 81
  38. 96
  39. 79
  40. 9.8

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