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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 654 · 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.√48 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 7.2
  2. 2.Best estimate of 4180 ÷ 51? (a) 84 (b) 840 (c) 8400
  3. 3.Best estimate of 1936 ÷ 36? (a) 480 (b) 4800 (c) 48
  4. 4.√61 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.5 (d) 7.7
  5. 5.Best estimate of 1728 ÷ 28? (a) 580 (b) 5800 (c) 58
  6. 6.Best estimate of 2217 ÷ 36? (a) 55 (b) 550 (c) 5500
  7. 7.Best estimate of 2824 ÷ 31? (a) 940 (b) 94 (c) 9400
  8. 8.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  9. 9.√80 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 8.7
  10. 10.Best estimate of 868 ÷ 26? (a) 290 (b) 29 (c) 2900
  11. 11.√74 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  12. 12.Best estimate of 3824 ÷ 46? (a) 7600 (b) 76 (c) 760
  13. 13.Best estimate of 2325 ÷ 32? (a) 78 (b) 7800 (c) 780
  14. 14.Best estimate of 1399 ÷ 46? (a) 280 (b) 28 (c) 2800
  15. 15.Best estimate of 836 ÷ 38? (a) 21 (b) 210 (c) 2100
  16. 16.√37 to 1 decimal place? (a) 6.2 (b) 5.9 (c) 6.0 (d) 6.1
  17. 17.Best estimate of 2478 ÷ 53? (a) 50 (b) 5000 (c) 500
  18. 18.Best estimate of 6185 ÷ 84? (a) 77 (b) 770 (c) 7700
  19. 19.Best estimate of 3598 ÷ 39? (a) 90 (b) 9000 (c) 900
  20. 20.Best estimate of 4669 ÷ 63? (a) 780 (b) 7800 (c) 78
  21. 21.√47 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  22. 22.√34 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 5.8 (d) 6.0
  23. 23.Best estimate of 1357 ÷ 42? (a) 340 (b) 34 (c) 3400
  24. 24.Best estimate of 2661 ÷ 34? (a) 890 (b) 8900 (c) 89
  25. 25.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  26. 26.Best estimate of 3749 ÷ 74? (a) 54 (b) 5400 (c) 540
  27. 27.Best estimate of 3683 ÷ 57? (a) 6100 (b) 610 (c) 61
  28. 28.√62 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 7.9
  29. 29.√50 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  30. 30.√28 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.6 (d) 5.4
  31. 31.√38 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 6.2
  32. 32.Best estimate of 3517 ÷ 76? (a) 440 (b) 44 (c) 4400
  33. 33.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.6 (d) 5.7
  34. 34.Best estimate of 1220 ÷ 43? (a) 3100 (b) 310 (c) 31
  35. 35.Best estimate of 986 ÷ 82? (a) 1200 (b) 12 (c) 120
  36. 36.Best estimate of 2746 ÷ 82? (a) 3400 (b) 340 (c) 34
  37. 37.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.4
  38. 38.Best estimate of 3096 ÷ 41? (a) 770 (b) 77 (c) 7700
  39. 39.Best estimate of 1285 ÷ 81? (a) 16 (b) 160 (c) 1600
  40. 40.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1

Answer key

  1. 6.9
  2. 84
  3. 48
  4. 7.8
  5. 58
  6. 55
  7. 94
  8. 9.7
  9. 8.9
  10. 29
  11. 8.6
  12. 76
  13. 78
  14. 28
  15. 21
  16. 6.1
  17. 50
  18. 77
  19. 90
  20. 78
  21. 6.9
  22. 5.8
  23. 34
  24. 89
  25. 5.6
  26. 54
  27. 61
  28. 7.9
  29. 7.1
  30. 5.3
  31. 6.2
  32. 44
  33. 5.7
  34. 31
  35. 12
  36. 34
  37. 5.1
  38. 77
  39. 16
  40. 9.1

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