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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 544 · 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.√87 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  2. 2.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  3. 3.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 6.1
  4. 4.Best estimate of 5159 ÷ 56? (a) 8600 (b) 860 (c) 86
  5. 5.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.3 (d) 5.4
  6. 6.Best estimate of 6011 ÷ 69? (a) 860 (b) 8600 (c) 86
  7. 7.√58 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.8
  8. 8.Best estimate of 2772 ÷ 72? (a) 4000 (b) 40 (c) 400
  9. 9.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.4 (d) 5.1
  10. 10.Best estimate of 5189 ÷ 64? (a) 860 (b) 8600 (c) 86
  11. 11.√55 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.4 (d) 7.6
  12. 12.Best estimate of 1770 ÷ 29? (a) 59 (b) 5900 (c) 590
  13. 13.Best estimate of 1828 ÷ 58? (a) 30 (b) 3000 (c) 300
  14. 14.Best estimate of 2437 ÷ 43? (a) 6100 (b) 610 (c) 61
  15. 15.Best estimate of 2540 ÷ 37? (a) 64 (b) 640 (c) 6400
  16. 16.Best estimate of 3474 ÷ 62? (a) 5800 (b) 580 (c) 58
  17. 17.Best estimate of 4144 ÷ 56? (a) 6900 (b) 690 (c) 69
  18. 18.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.9
  19. 19.Best estimate of 3502 ÷ 49? (a) 70 (b) 700 (c) 7000
  20. 20.Best estimate of 2290 ÷ 78? (a) 290 (b) 2900 (c) 29
  21. 21.Best estimate of 1575 ÷ 64? (a) 260 (b) 26 (c) 2600
  22. 22.Best estimate of 1941 ÷ 26? (a) 6500 (b) 65 (c) 650
  23. 23.Best estimate of 6723 ÷ 76? (a) 84 (b) 8400 (c) 840
  24. 24.Best estimate of 3051 ÷ 82? (a) 3800 (b) 380 (c) 38
  25. 25.Best estimate of 1078 ÷ 24? (a) 5400 (b) 540 (c) 54
  26. 26.Best estimate of 3081 ÷ 72? (a) 4400 (b) 44 (c) 440
  27. 27.√77 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  28. 28.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 7.0 (d) 6.8
  29. 29.Best estimate of 2622 ÷ 37? (a) 66 (b) 6600 (c) 660
  30. 30.Best estimate of 1984 ÷ 33? (a) 6600 (b) 66 (c) 660
  31. 31.Best estimate of 6123 ÷ 68? (a) 870 (b) 87 (c) 8700
  32. 32.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.2
  33. 33.√44 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  34. 34.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 5.9
  35. 35.Best estimate of 567 ÷ 37? (a) 140 (b) 14 (c) 1400
  36. 36.Best estimate of 4203 ÷ 87? (a) 470 (b) 4700 (c) 47
  37. 37.√51 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 7.2
  38. 38.√50 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 7.2
  39. 39.√75 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  40. 40.Best estimate of 1184 ÷ 43? (a) 3000 (b) 30 (c) 300

Answer key

  1. 9.3
  2. 5.3
  3. 5.9
  4. 86
  5. 5.6
  6. 86
  7. 7.6
  8. 40
  9. 5.1
  10. 86
  11. 7.4
  12. 59
  13. 30
  14. 61
  15. 64
  16. 58
  17. 69
  18. 9.6
  19. 70
  20. 29
  21. 26
  22. 65
  23. 84
  24. 38
  25. 54
  26. 44
  27. 8.8
  28. 6.7
  29. 66
  30. 66
  31. 87
  32. 8.4
  33. 6.6
  34. 6.1
  35. 14
  36. 47
  37. 7.1
  38. 7.1
  39. 8.7
  40. 30

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