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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 178 · 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 1940 ÷ 59? (a) 3200 (b) 320 (c) 32
  2. 2.Best estimate of 2438 ÷ 61? (a) 410 (b) 41 (c) 4100
  3. 3.Best estimate of 1482 ÷ 44? (a) 37 (b) 370 (c) 3700
  4. 4.√20 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  5. 5.Best estimate of 5115 ÷ 73? (a) 730 (b) 7300 (c) 73
  6. 6.Best estimate of 1325 ÷ 42? (a) 3300 (b) 33 (c) 330
  7. 7.√46 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 6.7
  8. 8.Best estimate of 4366 ÷ 46? (a) 870 (b) 8700 (c) 87
  9. 9.Best estimate of 960 ÷ 37? (a) 2400 (b) 24 (c) 240
  10. 10.Best estimate of 1893 ÷ 67? (a) 270 (b) 2700 (c) 27
  11. 11.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.7 (d) 6.0
  12. 12.Best estimate of 695 ÷ 24? (a) 3500 (b) 35 (c) 350
  13. 13.Best estimate of 3952 ÷ 62? (a) 66 (b) 660 (c) 6600
  14. 14.√45 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  15. 15.√26 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 5.2
  16. 16.Best estimate of 2490 ÷ 66? (a) 3600 (b) 360 (c) 36
  17. 17.Best estimate of 2014 ÷ 37? (a) 5000 (b) 500 (c) 50
  18. 18.Best estimate of 2509 ÷ 32? (a) 840 (b) 8400 (c) 84
  19. 19.√58 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  20. 20.√21 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.3 (d) 4.5
  21. 21.√38 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 5.9
  22. 22.Best estimate of 2064 ÷ 71? (a) 29 (b) 290 (c) 2900
  23. 23.√42 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.2
  24. 24.√65 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.2 (d) 8.1
  25. 25.Best estimate of 5904 ÷ 62? (a) 98 (b) 9800 (c) 980
  26. 26.Best estimate of 1433 ÷ 46? (a) 2900 (b) 29 (c) 290
  27. 27.√77 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 8.6
  28. 28.Best estimate of 6113 ÷ 84? (a) 760 (b) 7600 (c) 76
  29. 29.Best estimate of 4668 ÷ 78? (a) 580 (b) 5800 (c) 58
  30. 30.Best estimate of 3504 ÷ 74? (a) 50 (b) 500 (c) 5000
  31. 31.Best estimate of 1116 ÷ 54? (a) 220 (b) 22 (c) 2200
  32. 32.√52 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.2
  33. 33.Best estimate of 5049 ÷ 78? (a) 63 (b) 6300 (c) 630
  34. 34.Best estimate of 1856 ÷ 21? (a) 9300 (b) 93 (c) 930
  35. 35.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.5
  36. 36.√66 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.4 (d) 8.3
  37. 37.√27 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.2 (d) 5.4
  38. 38.Best estimate of 1075 ÷ 39? (a) 270 (b) 27 (c) 2700
  39. 39.√83 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 9.1
  40. 40.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.4 (d) 5.5

Answer key

  1. 32
  2. 41
  3. 37
  4. 4.5
  5. 73
  6. 33
  7. 6.8
  8. 87
  9. 24
  10. 27
  11. 5.9
  12. 35
  13. 66
  14. 6.7
  15. 5.1
  16. 36
  17. 50
  18. 84
  19. 7.6
  20. 4.6
  21. 6.2
  22. 29
  23. 6.5
  24. 8.1
  25. 98
  26. 29
  27. 8.8
  28. 76
  29. 58
  30. 50
  31. 22
  32. 7.2
  33. 63
  34. 93
  35. 6.3
  36. 8.1
  37. 5.2
  38. 27
  39. 9.1
  40. 5.6

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