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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 682 · 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 1133 ÷ 24? (a) 570 (b) 57 (c) 5700
  2. 2.√44 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  3. 3.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.9
  4. 4.Best estimate of 6200 ÷ 83? (a) 780 (b) 7800 (c) 78
  5. 5.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  6. 6.√48 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.9 (d) 6.8
  7. 7.√88 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  8. 8.Best estimate of 2409 ÷ 27? (a) 800 (b) 8000 (c) 80
  9. 9.√86 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  10. 10.Best estimate of 2272 ÷ 87? (a) 25 (b) 2500 (c) 250
  11. 11.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.5 (d) 7.4
  12. 12.√89 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.3
  13. 13.Best estimate of 839 ÷ 58? (a) 140 (b) 14 (c) 1400
  14. 14.Best estimate of 7823 ÷ 88? (a) 8700 (b) 870 (c) 87
  15. 15.Best estimate of 1275 ÷ 43? (a) 32 (b) 320 (c) 3200
  16. 16.Best estimate of 403 ÷ 24? (a) 2000 (b) 20 (c) 200
  17. 17.Best estimate of 2180 ÷ 56? (a) 360 (b) 3600 (c) 36
  18. 18.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 4.8
  19. 19.Best estimate of 1502 ÷ 47? (a) 300 (b) 3000 (c) 30
  20. 20.√66 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  21. 21.√85 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  22. 22.Best estimate of 483 ÷ 37? (a) 120 (b) 1200 (c) 12
  23. 23.√23 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.9
  24. 24.Best estimate of 4758 ÷ 66? (a) 6800 (b) 68 (c) 680
  25. 25.Best estimate of 2317 ÷ 32? (a) 77 (b) 770 (c) 7700
  26. 26.Best estimate of 3185 ÷ 39? (a) 8000 (b) 800 (c) 80
  27. 27.Best estimate of 3808 ÷ 51? (a) 76 (b) 760 (c) 7600
  28. 28.Best estimate of 4765 ÷ 61? (a) 790 (b) 79 (c) 7900
  29. 29.Best estimate of 4677 ÷ 53? (a) 94 (b) 940 (c) 9400
  30. 30.Best estimate of 4170 ÷ 76? (a) 5200 (b) 520 (c) 52
  31. 31.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.8
  32. 32.Best estimate of 3521 ÷ 43? (a) 88 (b) 8800 (c) 880
  33. 33.Best estimate of 2507 ÷ 48? (a) 500 (b) 5000 (c) 50
  34. 34.Best estimate of 6591 ÷ 69? (a) 9400 (b) 94 (c) 940
  35. 35.√84 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.5 (d) 9.3
  36. 36.√75 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  37. 37.Best estimate of 535 ÷ 26? (a) 1800 (b) 180 (c) 18
  38. 38.√62 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  39. 39.Best estimate of 603 ÷ 47? (a) 1200 (b) 120 (c) 12
  40. 40.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.8

Answer key

  1. 57
  2. 6.6
  3. 7.6
  4. 78
  5. 6.3
  6. 6.9
  7. 9.4
  8. 80
  9. 9.3
  10. 25
  11. 7.4
  12. 9.4
  13. 14
  14. 87
  15. 32
  16. 20
  17. 36
  18. 5.1
  19. 30
  20. 8.1
  21. 9.2
  22. 12
  23. 4.8
  24. 68
  25. 77
  26. 80
  27. 76
  28. 79
  29. 94
  30. 52
  31. 4.7
  32. 88
  33. 50
  34. 94
  35. 9.2
  36. 8.7
  37. 18
  38. 7.9
  39. 12
  40. 5.5

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