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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 767 · 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) 5.8 (c) 5.9 (d) 5.6
  2. 2.Best estimate of 999 ÷ 51? (a) 2000 (b) 20 (c) 200
  3. 3.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.5
  4. 4.Best estimate of 5160 ÷ 82? (a) 65 (b) 6500 (c) 650
  5. 5.√46 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 7.0
  6. 6.Best estimate of 5552 ÷ 69? (a) 790 (b) 79 (c) 7900
  7. 7.√45 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.6 (d) 6.7
  8. 8.Best estimate of 2127 ÷ 46? (a) 4300 (b) 430 (c) 43
  9. 9.Best estimate of 3278 ÷ 84? (a) 41 (b) 4100 (c) 410
  10. 10.√32 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.7 (d) 5.5
  11. 11.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  12. 12.√84 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0
  13. 13.Best estimate of 655 ÷ 28? (a) 22 (b) 220 (c) 2200
  14. 14.Best estimate of 3300 ÷ 36? (a) 830 (b) 83 (c) 8300
  15. 15.Best estimate of 4347 ÷ 86? (a) 4800 (b) 480 (c) 48
  16. 16.Best estimate of 1930 ÷ 26? (a) 640 (b) 6400 (c) 64
  17. 17.Best estimate of 7092 ÷ 87? (a) 790 (b) 7900 (c) 79
  18. 18.Best estimate of 1009 ÷ 29? (a) 340 (b) 3400 (c) 34
  19. 19.Best estimate of 798 ÷ 21? (a) 400 (b) 4000 (c) 40
  20. 20.√31 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.6 (d) 5.4
  21. 21.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.5 (d) 8.4
  22. 22.Best estimate of 747 ÷ 31? (a) 2500 (b) 250 (c) 25
  23. 23.Best estimate of 5618 ÷ 76? (a) 700 (b) 7000 (c) 70
  24. 24.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.8 (d) 7.9
  25. 25.Best estimate of 3396 ÷ 61? (a) 5700 (b) 57 (c) 570
  26. 26.Best estimate of 1083 ÷ 32? (a) 360 (b) 36 (c) 3600
  27. 27.Best estimate of 888 ÷ 46? (a) 1800 (b) 180 (c) 18
  28. 28.Best estimate of 2359 ÷ 71? (a) 34 (b) 340 (c) 3400
  29. 29.Best estimate of 2454 ÷ 27? (a) 8200 (b) 820 (c) 82
  30. 30.Best estimate of 3508 ÷ 74? (a) 5000 (b) 500 (c) 50
  31. 31.Best estimate of 1003 ÷ 33? (a) 33 (b) 3300 (c) 330
  32. 32.Best estimate of 5646 ÷ 68? (a) 8100 (b) 810 (c) 81
  33. 33.√58 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  34. 34.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.2 (d) 5.0
  35. 35.Best estimate of 5219 ÷ 72? (a) 7500 (b) 750 (c) 75
  36. 36.√50 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 7.1
  37. 37.Best estimate of 5749 ÷ 83? (a) 7200 (b) 72 (c) 720
  38. 38.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  39. 39.Best estimate of 2272 ÷ 53? (a) 4500 (b) 450 (c) 45
  40. 40.Best estimate of 5756 ÷ 67? (a) 82 (b) 820 (c) 8200

Answer key

  1. 5.8
  2. 20
  3. 7.4
  4. 65
  5. 6.8
  6. 79
  7. 6.7
  8. 43
  9. 41
  10. 5.7
  11. 9.4
  12. 9.2
  13. 22
  14. 83
  15. 48
  16. 64
  17. 79
  18. 34
  19. 40
  20. 5.6
  21. 8.3
  22. 25
  23. 70
  24. 8.1
  25. 57
  26. 36
  27. 18
  28. 34
  29. 82
  30. 50
  31. 33
  32. 81
  33. 7.6
  34. 5.1
  35. 75
  36. 7.1
  37. 72
  38. 9.7
  39. 45
  40. 82

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