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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 358 · 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.√27 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.0 (d) 5.2
  2. 2.Best estimate of 4275 ÷ 74? (a) 61 (b) 6100 (c) 610
  3. 3.Best estimate of 738 ÷ 52? (a) 150 (b) 15 (c) 1500
  4. 4.Best estimate of 1105 ÷ 62? (a) 1800 (b) 18 (c) 180
  5. 5.Best estimate of 3210 ÷ 36? (a) 80 (b) 800 (c) 8000
  6. 6.Best estimate of 318 ÷ 26? (a) 1100 (b) 110 (c) 11
  7. 7.Best estimate of 1837 ÷ 46? (a) 3700 (b) 370 (c) 37
  8. 8.Best estimate of 1790 ÷ 51? (a) 36 (b) 3600 (c) 360
  9. 9.Best estimate of 1916 ÷ 36? (a) 48 (b) 480 (c) 4800
  10. 10.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.6
  11. 11.√43 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  12. 12.Best estimate of 5276 ÷ 76? (a) 66 (b) 6600 (c) 660
  13. 13.Best estimate of 4132 ÷ 62? (a) 690 (b) 6900 (c) 69
  14. 14.Best estimate of 1854 ÷ 21? (a) 9300 (b) 93 (c) 930
  15. 15.Best estimate of 2120 ÷ 27? (a) 71 (b) 710 (c) 7100
  16. 16.Best estimate of 1070 ÷ 31? (a) 360 (b) 36 (c) 3600
  17. 17.Best estimate of 2491 ÷ 64? (a) 420 (b) 42 (c) 4200
  18. 18.Best estimate of 3000 ÷ 36? (a) 750 (b) 7500 (c) 75
  19. 19.√41 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.3
  20. 20.Best estimate of 718 ÷ 31? (a) 2400 (b) 240 (c) 24
  21. 21.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  22. 22.√84 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 9.3
  23. 23.Best estimate of 6693 ÷ 76? (a) 840 (b) 84 (c) 8400
  24. 24.Best estimate of 1702 ÷ 26? (a) 5700 (b) 570 (c) 57
  25. 25.√21 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.3 (d) 4.6
  26. 26.√28 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.4 (d) 5.5
  27. 27.Best estimate of 1815 ÷ 31? (a) 6100 (b) 610 (c) 61
  28. 28.Best estimate of 1405 ÷ 54? (a) 2800 (b) 28 (c) 280
  29. 29.Best estimate of 3245 ÷ 43? (a) 8100 (b) 810 (c) 81
  30. 30.Best estimate of 1224 ÷ 84? (a) 1500 (b) 15 (c) 150
  31. 31.√79 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.0 (d) 9.2
  32. 32.Best estimate of 1226 ÷ 22? (a) 61 (b) 610 (c) 6100
  33. 33.√53 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.3 (d) 7.4
  34. 34.Best estimate of 2547 ÷ 86? (a) 280 (b) 28 (c) 2800
  35. 35.√50 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 6.8
  36. 36.√87 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.1
  37. 37.Best estimate of 2201 ÷ 84? (a) 2800 (b) 28 (c) 280
  38. 38.Best estimate of 2460 ÷ 76? (a) 31 (b) 3100 (c) 310
  39. 39.√22 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  40. 40.Best estimate of 2063 ÷ 79? (a) 260 (b) 26 (c) 2600

Answer key

  1. 5.2
  2. 61
  3. 15
  4. 18
  5. 80
  6. 11
  7. 37
  8. 36
  9. 48
  10. 8.3
  11. 6.6
  12. 66
  13. 69
  14. 93
  15. 71
  16. 36
  17. 42
  18. 75
  19. 6.4
  20. 24
  21. 5.6
  22. 9.2
  23. 84
  24. 57
  25. 4.6
  26. 5.3
  27. 61
  28. 28
  29. 81
  30. 15
  31. 8.9
  32. 61
  33. 7.3
  34. 28
  35. 7.1
  36. 9.3
  37. 28
  38. 31
  39. 4.7
  40. 26

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