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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 556 · 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 1598 ÷ 52? (a) 3200 (b) 320 (c) 32
  2. 2.Best estimate of 3805 ÷ 54? (a) 7600 (b) 760 (c) 76
  3. 3.Best estimate of 1150 ÷ 46? (a) 23 (b) 2300 (c) 230
  4. 4.√27 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.1 (d) 5.3
  5. 5.√48 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  6. 6.Best estimate of 4830 ÷ 53? (a) 9700 (b) 970 (c) 97
  7. 7.√88 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  8. 8.Best estimate of 2127 ÷ 66? (a) 30 (b) 300 (c) 3000
  9. 9.√72 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.3
  10. 10.Best estimate of 2081 ÷ 26? (a) 69 (b) 6900 (c) 690
  11. 11.Best estimate of 4462 ÷ 74? (a) 640 (b) 6400 (c) 64
  12. 12.√79 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  13. 13.Best estimate of 4197 ÷ 58? (a) 70 (b) 7000 (c) 700
  14. 14.Best estimate of 2442 ÷ 64? (a) 4100 (b) 41 (c) 410
  15. 15.Best estimate of 1047 ÷ 37? (a) 260 (b) 26 (c) 2600
  16. 16.√41 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  17. 17.√35 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 5.8 (d) 6.0
  18. 18.Best estimate of 2483 ÷ 56? (a) 41 (b) 410 (c) 4100
  19. 19.√83 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.0
  20. 20.√45 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  21. 21.√84 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  22. 22.Best estimate of 3336 ÷ 44? (a) 8300 (b) 830 (c) 83
  23. 23.Best estimate of 1443 ÷ 72? (a) 21 (b) 2100 (c) 210
  24. 24.Best estimate of 819 ÷ 26? (a) 2700 (b) 27 (c) 270
  25. 25.√71 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  26. 26.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  27. 27.√28 to 1 decimal place? (a) 5.3 (b) 5.6 (c) 5.4 (d) 5.5
  28. 28.Best estimate of 1511 ÷ 68? (a) 22 (b) 2200 (c) 220
  29. 29.√59 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7
  30. 30.√47 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  31. 31.√55 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  32. 32.Best estimate of 2855 ÷ 53? (a) 57 (b) 570 (c) 5700
  33. 33.√34 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.8 (d) 5.9
  34. 34.Best estimate of 4807 ÷ 83? (a) 60 (b) 600 (c) 6000
  35. 35.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.5
  36. 36.Best estimate of 2243 ÷ 58? (a) 37 (b) 370 (c) 3700
  37. 37.Best estimate of 2763 ÷ 33? (a) 92 (b) 920 (c) 9200
  38. 38.Best estimate of 1398 ÷ 43? (a) 350 (b) 35 (c) 3500
  39. 39.Best estimate of 1670 ÷ 58? (a) 280 (b) 28 (c) 2800
  40. 40.√82 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1

Answer key

  1. 32
  2. 76
  3. 23
  4. 5.2
  5. 6.9
  6. 97
  7. 9.4
  8. 30
  9. 8.5
  10. 69
  11. 64
  12. 8.9
  13. 70
  14. 41
  15. 26
  16. 6.4
  17. 5.9
  18. 41
  19. 9.1
  20. 6.7
  21. 9.2
  22. 83
  23. 21
  24. 27
  25. 8.4
  26. 5.5
  27. 5.3
  28. 22
  29. 7.7
  30. 6.9
  31. 7.4
  32. 57
  33. 5.8
  34. 60
  35. 6.2
  36. 37
  37. 92
  38. 35
  39. 28
  40. 9.1

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