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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 637 · 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.√77 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 8.8
  2. 2.√80 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 9.0 (d) 8.8
  3. 3.Best estimate of 3088 ÷ 56? (a) 5100 (b) 51 (c) 510
  4. 4.√26 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.2 (d) 5.0
  5. 5.Best estimate of 7705 ÷ 88? (a) 860 (b) 86 (c) 8600
  6. 6.√38 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.3 (d) 6.4
  7. 7.√22 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  8. 8.Best estimate of 1901 ÷ 21? (a) 9500 (b) 95 (c) 950
  9. 9.Best estimate of 970 ÷ 68? (a) 14 (b) 140 (c) 1400
  10. 10.√74 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.4 (d) 8.5
  11. 11.Best estimate of 811 ÷ 21? (a) 410 (b) 41 (c) 4100
  12. 12.√72 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  13. 13.√75 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  14. 14.√44 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.5
  15. 15.Best estimate of 1082 ÷ 46? (a) 22 (b) 2200 (c) 220
  16. 16.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.5 (d) 5.4
  17. 17.Best estimate of 1107 ÷ 71? (a) 160 (b) 16 (c) 1600
  18. 18.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 6.3
  19. 19.√82 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 9.1
  20. 20.Best estimate of 4406 ÷ 86? (a) 490 (b) 4900 (c) 49
  21. 21.Best estimate of 1942 ÷ 41? (a) 490 (b) 4900 (c) 49
  22. 22.√32 to 1 decimal place? (a) 5.7 (b) 6.0 (c) 5.9 (d) 5.8
  23. 23.√41 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  24. 24.√53 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 7.3
  25. 25.Best estimate of 5864 ÷ 66? (a) 84 (b) 840 (c) 8400
  26. 26.Best estimate of 1522 ÷ 37? (a) 3800 (b) 38 (c) 380
  27. 27.Best estimate of 393 ÷ 21? (a) 200 (b) 20 (c) 2000
  28. 28.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 9.7
  29. 29.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  30. 30.√98 to 1 decimal place? (a) 10.0 (b) 10.2 (c) 9.9 (d) 10.1
  31. 31.√70 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.2
  32. 32.√85 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.5
  33. 33.Best estimate of 3319 ÷ 36? (a) 8300 (b) 83 (c) 830
  34. 34.Best estimate of 5804 ÷ 67? (a) 83 (b) 830 (c) 8300
  35. 35.√88 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  36. 36.Best estimate of 617 ÷ 32? (a) 21 (b) 210 (c) 2100
  37. 37.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  38. 38.Best estimate of 3818 ÷ 41? (a) 95 (b) 9500 (c) 950
  39. 39.√50 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.1 (d) 7.2
  40. 40.Best estimate of 2005 ÷ 28? (a) 67 (b) 6700 (c) 670

Answer key

  1. 8.8
  2. 8.9
  3. 51
  4. 5.1
  5. 86
  6. 6.2
  7. 4.7
  8. 95
  9. 14
  10. 8.6
  11. 41
  12. 8.5
  13. 8.7
  14. 6.6
  15. 22
  16. 5.2
  17. 16
  18. 6.1
  19. 9.1
  20. 49
  21. 49
  22. 5.7
  23. 6.4
  24. 7.3
  25. 84
  26. 38
  27. 20
  28. 9.8
  29. 9.7
  30. 9.9
  31. 8.4
  32. 9.2
  33. 83
  34. 83
  35. 9.4
  36. 21
  37. 5.4
  38. 95
  39. 7.1
  40. 67

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