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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 618 · 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 1861 ÷ 48? (a) 37 (b) 370 (c) 3700
  2. 2.Best estimate of 3379 ÷ 36? (a) 8400 (b) 84 (c) 840
  3. 3.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  4. 4.Best estimate of 1172 ÷ 69? (a) 170 (b) 17 (c) 1700
  5. 5.√58 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  6. 6.√65 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.1
  7. 7.Best estimate of 1085 ÷ 42? (a) 2700 (b) 27 (c) 270
  8. 8.Best estimate of 495 ÷ 41? (a) 12 (b) 120 (c) 1200
  9. 9.Best estimate of 789 ÷ 27? (a) 2600 (b) 260 (c) 26
  10. 10.Best estimate of 1381 ÷ 63? (a) 23 (b) 230 (c) 2300
  11. 11.√24 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  12. 12.√55 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.2
  13. 13.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.9
  14. 14.√61 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  15. 15.√29 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  16. 16.√44 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  17. 17.Best estimate of 6007 ÷ 76? (a) 75 (b) 7500 (c) 750
  18. 18.Best estimate of 2624 ÷ 89? (a) 29 (b) 290 (c) 2900
  19. 19.Best estimate of 4273 ÷ 67? (a) 610 (b) 6100 (c) 61
  20. 20.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  21. 21.√83 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  22. 22.Best estimate of 3213 ÷ 37? (a) 8000 (b) 80 (c) 800
  23. 23.Best estimate of 4396 ÷ 67? (a) 630 (b) 63 (c) 6300
  24. 24.√46 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  25. 25.√52 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.5
  26. 26.Best estimate of 1834 ÷ 27? (a) 610 (b) 61 (c) 6100
  27. 27.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.5 (d) 4.8
  28. 28.Best estimate of 2889 ÷ 42? (a) 72 (b) 720 (c) 7200
  29. 29.Best estimate of 2171 ÷ 39? (a) 5400 (b) 54 (c) 540
  30. 30.Best estimate of 7075 ÷ 86? (a) 79 (b) 790 (c) 7900
  31. 31.Best estimate of 1167 ÷ 83? (a) 150 (b) 15 (c) 1500
  32. 32.Best estimate of 1847 ÷ 26? (a) 620 (b) 6200 (c) 62
  33. 33.√63 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  34. 34.Best estimate of 1161 ÷ 28? (a) 390 (b) 39 (c) 3900
  35. 35.Best estimate of 4520 ÷ 81? (a) 5700 (b) 570 (c) 57
  36. 36.Best estimate of 2121 ÷ 36? (a) 530 (b) 53 (c) 5300
  37. 37.Best estimate of 1883 ÷ 39? (a) 470 (b) 4700 (c) 47
  38. 38.Best estimate of 348 ÷ 26? (a) 120 (b) 12 (c) 1200
  39. 39.Best estimate of 4639 ÷ 82? (a) 580 (b) 5800 (c) 58
  40. 40.√62 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 7.6

Answer key

  1. 37
  2. 84
  3. 9.1
  4. 17
  5. 7.6
  6. 8.1
  7. 27
  8. 12
  9. 26
  10. 23
  11. 4.9
  12. 7.4
  13. 5.8
  14. 7.8
  15. 5.4
  16. 6.6
  17. 75
  18. 29
  19. 61
  20. 6.3
  21. 9.1
  22. 80
  23. 63
  24. 6.8
  25. 7.2
  26. 61
  27. 4.6
  28. 72
  29. 54
  30. 79
  31. 15
  32. 62
  33. 7.9
  34. 39
  35. 57
  36. 53
  37. 47
  38. 12
  39. 58
  40. 7.9

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