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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 340 · 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.√52 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 7.3
  2. 2.Best estimate of 3260 ÷ 36? (a) 82 (b) 820 (c) 8200
  3. 3.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 10.1
  4. 4.√69 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  5. 5.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 7.6
  6. 6.√59 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.5
  7. 7.√63 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  8. 8.√83 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  9. 9.√96 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  10. 10.Best estimate of 5266 ÷ 66? (a) 7500 (b) 750 (c) 75
  11. 11.√76 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9
  12. 12.Best estimate of 1445 ÷ 36? (a) 360 (b) 3600 (c) 36
  13. 13.√87 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.0
  14. 14.Best estimate of 5468 ÷ 78? (a) 680 (b) 68 (c) 6800
  15. 15.√35 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 5.7
  16. 16.Best estimate of 3412 ÷ 56? (a) 5700 (b) 570 (c) 57
  17. 17.√55 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.4 (d) 7.6
  18. 18.Best estimate of 2362 ÷ 42? (a) 590 (b) 59 (c) 5900
  19. 19.Best estimate of 1831 ÷ 71? (a) 2600 (b) 260 (c) 26
  20. 20.√34 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 6.1
  21. 21.√77 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  22. 22.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.8
  23. 23.√50 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  24. 24.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.2 (d) 9.1
  25. 25.√47 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  26. 26.Best estimate of 4162 ÷ 52? (a) 8300 (b) 83 (c) 830
  27. 27.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.5
  28. 28.Best estimate of 4365 ÷ 48? (a) 8700 (b) 87 (c) 870
  29. 29.Best estimate of 3465 ÷ 39? (a) 8700 (b) 870 (c) 87
  30. 30.Best estimate of 7586 ÷ 82? (a) 95 (b) 950 (c) 9500
  31. 31.Best estimate of 3600 ÷ 61? (a) 6000 (b) 600 (c) 60
  32. 32.√20 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.5
  33. 33.Best estimate of 2469 ÷ 62? (a) 410 (b) 4100 (c) 41
  34. 34.Best estimate of 554 ÷ 46? (a) 1100 (b) 110 (c) 11
  35. 35.Best estimate of 1033 ÷ 86? (a) 1100 (b) 11 (c) 110
  36. 36.Best estimate of 3935 ÷ 63? (a) 660 (b) 66 (c) 6600
  37. 37.Best estimate of 2400 ÷ 82? (a) 300 (b) 30 (c) 3000
  38. 38.Best estimate of 1055 ÷ 48? (a) 21 (b) 2100 (c) 210
  39. 39.Best estimate of 698 ÷ 24? (a) 3500 (b) 350 (c) 35
  40. 40.Best estimate of 1630 ÷ 38? (a) 41 (b) 410 (c) 4100

Answer key

  1. 7.2
  2. 82
  3. 9.9
  4. 8.3
  5. 7.8
  6. 7.7
  7. 7.9
  8. 9.1
  9. 9.8
  10. 75
  11. 8.7
  12. 36
  13. 9.3
  14. 68
  15. 5.9
  16. 57
  17. 7.4
  18. 59
  19. 26
  20. 5.8
  21. 8.8
  22. 8.6
  23. 7.1
  24. 9.1
  25. 6.9
  26. 83
  27. 4.8
  28. 87
  29. 87
  30. 95
  31. 60
  32. 4.5
  33. 41
  34. 11
  35. 11
  36. 66
  37. 30
  38. 21
  39. 35
  40. 41

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