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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 959 · 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.√34 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.8
  2. 2.Best estimate of 5836 ÷ 63? (a) 970 (b) 97 (c) 9700
  3. 3.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 10.1
  4. 4.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  5. 5.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.8 (d) 7.7
  6. 6.√26 to 1 decimal place? (a) 5.4 (b) 5.1 (c) 5.3 (d) 5.2
  7. 7.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.9 (d) 7.7
  8. 8.Best estimate of 6053 ÷ 88? (a) 67 (b) 6700 (c) 670
  9. 9.Best estimate of 1512 ÷ 24? (a) 76 (b) 760 (c) 7600
  10. 10.Best estimate of 1459 ÷ 21? (a) 7300 (b) 730 (c) 73
  11. 11.Best estimate of 782 ÷ 23? (a) 390 (b) 39 (c) 3900
  12. 12.Best estimate of 4608 ÷ 69? (a) 6600 (b) 66 (c) 660
  13. 13.√80 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 8.6
  14. 14.Best estimate of 2145 ÷ 33? (a) 720 (b) 72 (c) 7200
  15. 15.Best estimate of 771 ÷ 22? (a) 390 (b) 39 (c) 3900
  16. 16.√89 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  17. 17.Best estimate of 2277 ÷ 56? (a) 3800 (b) 380 (c) 38
  18. 18.Best estimate of 370 ÷ 21? (a) 19 (b) 190 (c) 1900
  19. 19.Best estimate of 2099 ÷ 82? (a) 260 (b) 2600 (c) 26
  20. 20.Best estimate of 1751 ÷ 42? (a) 440 (b) 4400 (c) 44
  21. 21.Best estimate of 3027 ÷ 72? (a) 43 (b) 4300 (c) 430
  22. 22.Best estimate of 1940 ÷ 24? (a) 97 (b) 9700 (c) 970
  23. 23.√51 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  24. 24.√83 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.0
  25. 25.√66 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.1 (d) 8.0
  26. 26.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  27. 27.√40 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.2 (d) 6.3
  28. 28.Best estimate of 4133 ÷ 79? (a) 5200 (b) 520 (c) 52
  29. 29.Best estimate of 1156 ÷ 66? (a) 1700 (b) 170 (c) 17
  30. 30.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  31. 31.√63 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.9 (d) 7.8
  32. 32.√20 to 1 decimal place? (a) 4.5 (b) 4.3 (c) 4.6 (d) 4.4
  33. 33.Best estimate of 6604 ÷ 72? (a) 940 (b) 94 (c) 9400
  34. 34.Best estimate of 5265 ÷ 83? (a) 66 (b) 660 (c) 6600
  35. 35.Best estimate of 1021 ÷ 24? (a) 5100 (b) 51 (c) 510
  36. 36.Best estimate of 4459 ÷ 54? (a) 8900 (b) 89 (c) 890
  37. 37.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  38. 38.Best estimate of 3029 ÷ 84? (a) 380 (b) 3800 (c) 38
  39. 39.√21 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.3 (d) 4.4
  40. 40.Best estimate of 2848 ÷ 38? (a) 7100 (b) 71 (c) 710

Answer key

  1. 5.8
  2. 97
  3. 9.9
  4. 8.9
  5. 7.5
  6. 5.1
  7. 7.8
  8. 67
  9. 76
  10. 73
  11. 39
  12. 66
  13. 8.9
  14. 72
  15. 39
  16. 9.4
  17. 38
  18. 19
  19. 26
  20. 44
  21. 43
  22. 97
  23. 7.1
  24. 9.1
  25. 8.1
  26. 7.6
  27. 6.3
  28. 52
  29. 17
  30. 7.1
  31. 7.9
  32. 4.5
  33. 94
  34. 66
  35. 51
  36. 89
  37. 8.6
  38. 38
  39. 4.6
  40. 71

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