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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 215 · 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 1818 ÷ 23? (a) 910 (b) 9100 (c) 91
  2. 2.Best estimate of 2214 ÷ 33? (a) 74 (b) 740 (c) 7400
  3. 3.Best estimate of 7410 ÷ 78? (a) 930 (b) 9300 (c) 93
  4. 4.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.1
  5. 5.Best estimate of 2979 ÷ 34? (a) 990 (b) 9900 (c) 99
  6. 6.Best estimate of 3441 ÷ 77? (a) 4300 (b) 43 (c) 430
  7. 7.√66 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.2 (d) 8.1
  8. 8.Best estimate of 1819 ÷ 62? (a) 300 (b) 3000 (c) 30
  9. 9.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  10. 10.Best estimate of 3539 ÷ 62? (a) 590 (b) 59 (c) 5900
  11. 11.Best estimate of 4859 ÷ 51? (a) 9700 (b) 97 (c) 970
  12. 12.Best estimate of 4801 ÷ 83? (a) 6000 (b) 600 (c) 60
  13. 13.√74 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.6 (d) 8.5
  14. 14.Best estimate of 2280 ÷ 59? (a) 3800 (b) 380 (c) 38
  15. 15.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.9
  16. 16.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  17. 17.Best estimate of 812 ÷ 23? (a) 41 (b) 4100 (c) 410
  18. 18.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  19. 19.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  20. 20.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.1
  21. 21.√56 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  22. 22.√37 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  23. 23.Best estimate of 3106 ÷ 66? (a) 44 (b) 4400 (c) 440
  24. 24.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  25. 25.Best estimate of 1816 ÷ 29? (a) 610 (b) 6100 (c) 61
  26. 26.Best estimate of 1260 ÷ 42? (a) 320 (b) 32 (c) 3200
  27. 27.Best estimate of 5759 ÷ 82? (a) 7200 (b) 72 (c) 720
  28. 28.Best estimate of 4012 ÷ 64? (a) 670 (b) 67 (c) 6700
  29. 29.Best estimate of 1474 ÷ 53? (a) 29 (b) 290 (c) 2900
  30. 30.Best estimate of 2225 ÷ 29? (a) 740 (b) 7400 (c) 74
  31. 31.Best estimate of 1800 ÷ 23? (a) 9000 (b) 900 (c) 90
  32. 32.Best estimate of 4437 ÷ 88? (a) 4900 (b) 490 (c) 49
  33. 33.Best estimate of 618 ÷ 28? (a) 21 (b) 2100 (c) 210
  34. 34.√80 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 8.9
  35. 35.√72 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.6 (d) 8.5
  36. 36.√90 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  37. 37.Best estimate of 5139 ÷ 56? (a) 86 (b) 860 (c) 8600
  38. 38.Best estimate of 6766 ÷ 82? (a) 850 (b) 8500 (c) 85
  39. 39.Best estimate of 3580 ÷ 38? (a) 90 (b) 9000 (c) 900
  40. 40.Best estimate of 2480 ÷ 49? (a) 500 (b) 5000 (c) 50

Answer key

  1. 91
  2. 74
  3. 93
  4. 7.4
  5. 99
  6. 43
  7. 8.1
  8. 30
  9. 9.1
  10. 59
  11. 97
  12. 60
  13. 8.6
  14. 38
  15. 7.6
  16. 5.4
  17. 41
  18. 7.1
  19. 6.3
  20. 5.1
  21. 7.5
  22. 6.1
  23. 44
  24. 7.2
  25. 61
  26. 32
  27. 72
  28. 67
  29. 29
  30. 74
  31. 90
  32. 49
  33. 21
  34. 8.9
  35. 8.5
  36. 9.5
  37. 86
  38. 85
  39. 90
  40. 50

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