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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 852 · 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.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  2. 2.Best estimate of 1690 ÷ 26? (a) 5600 (b) 56 (c) 560
  3. 3.√86 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.6 (d) 9.5
  4. 4.√90 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.3
  5. 5.√40 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  6. 6.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.4 (d) 9.6
  7. 7.Best estimate of 4058 ÷ 81? (a) 51 (b) 5100 (c) 510
  8. 8.Best estimate of 6745 ÷ 82? (a) 84 (b) 840 (c) 8400
  9. 9.Best estimate of 5518 ÷ 59? (a) 9200 (b) 920 (c) 92
  10. 10.√78 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 8.9 (d) 9.0
  11. 11.√44 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.7 (d) 6.8
  12. 12.√82 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.2 (d) 9.0
  13. 13.Best estimate of 1106 ÷ 22? (a) 5500 (b) 55 (c) 550
  14. 14.Best estimate of 1777 ÷ 82? (a) 22 (b) 2200 (c) 220
  15. 15.Best estimate of 2207 ÷ 76? (a) 28 (b) 280 (c) 2800
  16. 16.Best estimate of 1209 ÷ 53? (a) 2400 (b) 240 (c) 24
  17. 17.√23 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.7 (d) 4.8
  18. 18.Best estimate of 2079 ÷ 74? (a) 3000 (b) 300 (c) 30
  19. 19.√71 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.3 (d) 8.2
  20. 20.Best estimate of 1331 ÷ 39? (a) 33 (b) 3300 (c) 330
  21. 21.Best estimate of 4735 ÷ 72? (a) 680 (b) 6800 (c) 68
  22. 22.Best estimate of 2521 ÷ 67? (a) 3600 (b) 36 (c) 360
  23. 23.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.5 (d) 6.4
  24. 24.Best estimate of 1621 ÷ 53? (a) 32 (b) 320 (c) 3200
  25. 25.Best estimate of 6093 ÷ 66? (a) 8700 (b) 87 (c) 870
  26. 26.√43 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 6.6
  27. 27.√37 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  28. 28.√92 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  29. 29.Best estimate of 2921 ÷ 32? (a) 970 (b) 9700 (c) 97
  30. 30.Best estimate of 510 ÷ 26? (a) 17 (b) 170 (c) 1700
  31. 31.Best estimate of 2267 ÷ 56? (a) 380 (b) 3800 (c) 38
  32. 32.Best estimate of 823 ÷ 24? (a) 410 (b) 4100 (c) 41
  33. 33.Best estimate of 1947 ÷ 43? (a) 49 (b) 490 (c) 4900
  34. 34.Best estimate of 877 ÷ 27? (a) 29 (b) 2900 (c) 290
  35. 35.√63 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  36. 36.Best estimate of 685 ÷ 21? (a) 34 (b) 3400 (c) 340
  37. 37.√67 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.3 (d) 8.2
  38. 38.Best estimate of 2717 ÷ 37? (a) 680 (b) 6800 (c) 68
  39. 39.Best estimate of 1078 ÷ 46? (a) 22 (b) 2200 (c) 220
  40. 40.Best estimate of 2436 ÷ 54? (a) 490 (b) 4900 (c) 49

Answer key

  1. 5.7
  2. 56
  3. 9.3
  4. 9.5
  5. 6.3
  6. 9.7
  7. 51
  8. 84
  9. 92
  10. 8.8
  11. 6.6
  12. 9.1
  13. 55
  14. 22
  15. 28
  16. 24
  17. 4.8
  18. 30
  19. 8.4
  20. 33
  21. 68
  22. 36
  23. 6.2
  24. 32
  25. 87
  26. 6.6
  27. 6.1
  28. 9.6
  29. 97
  30. 17
  31. 38
  32. 41
  33. 49
  34. 29
  35. 7.9
  36. 34
  37. 8.2
  38. 68
  39. 22
  40. 49

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