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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 181 · 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.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 4.9 (d) 5.1
  2. 2.√24 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 5.2
  3. 3.Best estimate of 881 ÷ 24? (a) 440 (b) 4400 (c) 44
  4. 4.√28 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.5
  5. 5.√30 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.4 (d) 5.5
  6. 6.Best estimate of 580 ÷ 24? (a) 29 (b) 2900 (c) 290
  7. 7.Best estimate of 1324 ÷ 21? (a) 6600 (b) 660 (c) 66
  8. 8.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.2 (d) 4.5
  9. 9.√92 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.7 (d) 9.6
  10. 10.Best estimate of 2577 ÷ 68? (a) 3700 (b) 370 (c) 37
  11. 11.√96 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.9 (d) 9.8
  12. 12.Best estimate of 3804 ÷ 43? (a) 9500 (b) 95 (c) 950
  13. 13.Best estimate of 2242 ÷ 27? (a) 750 (b) 75 (c) 7500
  14. 14.√80 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  15. 15.√47 to 1 decimal place? (a) 6.7 (b) 7.0 (c) 6.8 (d) 6.9
  16. 16.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 6.0 (d) 5.8
  17. 17.Best estimate of 3583 ÷ 76? (a) 45 (b) 4500 (c) 450
  18. 18.√56 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.2 (d) 7.3
  19. 19.Best estimate of 1723 ÷ 36? (a) 430 (b) 4300 (c) 43
  20. 20.Best estimate of 4454 ÷ 86? (a) 490 (b) 4900 (c) 49
  21. 21.Best estimate of 1879 ÷ 64? (a) 3100 (b) 31 (c) 310
  22. 22.Best estimate of 3230 ÷ 36? (a) 81 (b) 810 (c) 8100
  23. 23.Best estimate of 746 ÷ 32? (a) 250 (b) 25 (c) 2500
  24. 24.Best estimate of 5126 ÷ 76? (a) 6400 (b) 64 (c) 640
  25. 25.√58 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.4 (d) 7.7
  26. 26.Best estimate of 2947 ÷ 39? (a) 7400 (b) 74 (c) 740
  27. 27.√89 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  28. 28.√42 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.3
  29. 29.Best estimate of 1235 ÷ 33? (a) 4100 (b) 410 (c) 41
  30. 30.Best estimate of 313 ÷ 26? (a) 10 (b) 1000 (c) 100
  31. 31.√41 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  32. 32.Best estimate of 6956 ÷ 84? (a) 870 (b) 8700 (c) 87
  33. 33.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 8.0
  34. 34.Best estimate of 3762 ÷ 58? (a) 630 (b) 63 (c) 6300
  35. 35.Best estimate of 4242 ÷ 49? (a) 8500 (b) 850 (c) 85
  36. 36.Best estimate of 2386 ÷ 26? (a) 800 (b) 8000 (c) 80
  37. 37.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  38. 38.Best estimate of 3918 ÷ 82? (a) 49 (b) 4900 (c) 490
  39. 39.Best estimate of 5863 ÷ 67? (a) 840 (b) 8400 (c) 84
  40. 40.Best estimate of 4295 ÷ 49? (a) 8600 (b) 86 (c) 860

Answer key

  1. 5.1
  2. 4.9
  3. 44
  4. 5.3
  5. 5.5
  6. 29
  7. 66
  8. 4.5
  9. 9.6
  10. 37
  11. 9.8
  12. 95
  13. 75
  14. 8.9
  15. 6.9
  16. 5.8
  17. 45
  18. 7.5
  19. 43
  20. 49
  21. 31
  22. 81
  23. 25
  24. 64
  25. 7.6
  26. 74
  27. 9.4
  28. 6.5
  29. 41
  30. 10
  31. 6.4
  32. 87
  33. 7.9
  34. 63
  35. 85
  36. 80
  37. 6.2
  38. 49
  39. 84
  40. 86

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