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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 66 · 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.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.8
  2. 2.√77 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  3. 3.Best estimate of 3506 ÷ 38? (a) 8800 (b) 88 (c) 880
  4. 4.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  5. 5.Best estimate of 688 ÷ 28? (a) 230 (b) 2300 (c) 23
  6. 6.Best estimate of 1171 ÷ 36? (a) 29 (b) 290 (c) 2900
  7. 7.√35 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.2 (d) 6.0
  8. 8.√84 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.5
  9. 9.√63 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 8.0 (d) 7.8
  10. 10.Best estimate of 4540 ÷ 63? (a) 760 (b) 76 (c) 7600
  11. 11.Best estimate of 1502 ÷ 46? (a) 300 (b) 3000 (c) 30
  12. 12.√89 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.4 (d) 9.6
  13. 13.Best estimate of 6686 ÷ 84? (a) 8400 (b) 84 (c) 840
  14. 14.√85 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.1 (d) 9.2
  15. 15.Best estimate of 3393 ÷ 63? (a) 570 (b) 5700 (c) 57
  16. 16.Best estimate of 7228 ÷ 86? (a) 80 (b) 8000 (c) 800
  17. 17.Best estimate of 1648 ÷ 51? (a) 3300 (b) 33 (c) 330
  18. 18.Best estimate of 980 ÷ 37? (a) 25 (b) 250 (c) 2500
  19. 19.Best estimate of 567 ÷ 38? (a) 1400 (b) 14 (c) 140
  20. 20.√58 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.8 (d) 7.7
  21. 21.Best estimate of 6111 ÷ 76? (a) 7600 (b) 760 (c) 76
  22. 22.Best estimate of 1029 ÷ 27? (a) 34 (b) 340 (c) 3400
  23. 23.Best estimate of 7432 ÷ 88? (a) 830 (b) 83 (c) 8300
  24. 24.Best estimate of 3770 ÷ 71? (a) 5400 (b) 54 (c) 540
  25. 25.√65 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.0
  26. 26.Best estimate of 2549 ÷ 38? (a) 640 (b) 64 (c) 6400
  27. 27.√72 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.7
  28. 28.Best estimate of 898 ÷ 36? (a) 22 (b) 2200 (c) 220
  29. 29.√70 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.4
  30. 30.Best estimate of 3555 ÷ 41? (a) 8900 (b) 89 (c) 890
  31. 31.Best estimate of 4193 ÷ 86? (a) 4700 (b) 47 (c) 470
  32. 32.Best estimate of 3851 ÷ 58? (a) 640 (b) 64 (c) 6400
  33. 33.Best estimate of 1500 ÷ 22? (a) 75 (b) 750 (c) 7500
  34. 34.Best estimate of 2047 ÷ 57? (a) 3400 (b) 34 (c) 340
  35. 35.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.0
  36. 36.√30 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  37. 37.Best estimate of 3383 ÷ 39? (a) 850 (b) 8500 (c) 85
  38. 38.Best estimate of 7141 ÷ 87? (a) 79 (b) 790 (c) 7900
  39. 39.Best estimate of 1097 ÷ 41? (a) 2700 (b) 27 (c) 270
  40. 40.Best estimate of 864 ÷ 49? (a) 1700 (b) 17 (c) 170

Answer key

  1. 6.6
  2. 8.8
  3. 88
  4. 6.7
  5. 23
  6. 29
  7. 5.9
  8. 9.2
  9. 7.9
  10. 76
  11. 30
  12. 9.4
  13. 84
  14. 9.2
  15. 57
  16. 80
  17. 33
  18. 25
  19. 14
  20. 7.6
  21. 76
  22. 34
  23. 83
  24. 54
  25. 8.1
  26. 64
  27. 8.5
  28. 22
  29. 8.4
  30. 89
  31. 47
  32. 64
  33. 75
  34. 34
  35. 6.1
  36. 5.5
  37. 85
  38. 79
  39. 27
  40. 17

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