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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 991 · 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 912 ÷ 54? (a) 180 (b) 1800 (c) 18
  2. 2.√41 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.6 (d) 6.5
  3. 3.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.3
  4. 4.√58 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.6 (d) 7.7
  5. 5.Best estimate of 909 ÷ 28? (a) 30 (b) 300 (c) 3000
  6. 6.√78 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  7. 7.Best estimate of 1768 ÷ 26? (a) 590 (b) 59 (c) 5900
  8. 8.√77 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  9. 9.Best estimate of 2820 ÷ 82? (a) 350 (b) 3500 (c) 35
  10. 10.Best estimate of 2576 ÷ 29? (a) 860 (b) 86 (c) 8600
  11. 11.Best estimate of 1808 ÷ 84? (a) 230 (b) 23 (c) 2300
  12. 12.Best estimate of 2157 ÷ 79? (a) 270 (b) 27 (c) 2700
  13. 13.√53 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.2 (d) 7.3
  14. 14.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  15. 15.Best estimate of 5955 ÷ 71? (a) 8500 (b) 85 (c) 850
  16. 16.Best estimate of 2357 ÷ 31? (a) 79 (b) 790 (c) 7900
  17. 17.Best estimate of 4446 ÷ 56? (a) 7400 (b) 74 (c) 740
  18. 18.Best estimate of 1425 ÷ 62? (a) 24 (b) 2400 (c) 240
  19. 19.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.7
  20. 20.√27 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 5.2
  21. 21.Best estimate of 5784 ÷ 72? (a) 830 (b) 83 (c) 8300
  22. 22.Best estimate of 2181 ÷ 74? (a) 3100 (b) 310 (c) 31
  23. 23.Best estimate of 3822 ÷ 41? (a) 96 (b) 9600 (c) 960
  24. 24.Best estimate of 855 ÷ 27? (a) 2900 (b) 290 (c) 29
  25. 25.Best estimate of 1473 ÷ 64? (a) 250 (b) 2500 (c) 25
  26. 26.Best estimate of 1507 ÷ 76? (a) 19 (b) 1900 (c) 190
  27. 27.√30 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.6 (d) 5.7
  28. 28.Best estimate of 2404 ÷ 47? (a) 48 (b) 4800 (c) 480
  29. 29.Best estimate of 1160 ÷ 81? (a) 150 (b) 15 (c) 1500
  30. 30.√21 to 1 decimal place? (a) 4.6 (b) 4.3 (c) 4.5 (d) 4.4
  31. 31.Best estimate of 4667 ÷ 63? (a) 780 (b) 7800 (c) 78
  32. 32.√86 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  33. 33.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  34. 34.Best estimate of 1243 ÷ 67? (a) 180 (b) 1800 (c) 18
  35. 35.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.8
  36. 36.√31 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  37. 37.Best estimate of 1635 ÷ 89? (a) 180 (b) 1800 (c) 18
  38. 38.Best estimate of 4897 ÷ 73? (a) 7000 (b) 70 (c) 700
  39. 39.Best estimate of 569 ÷ 46? (a) 11 (b) 1100 (c) 110
  40. 40.√56 to 1 decimal place? (a) 7.2 (b) 7.5 (c) 7.3 (d) 7.4

Answer key

  1. 18
  2. 6.4
  3. 8.6
  4. 7.6
  5. 30
  6. 8.8
  7. 59
  8. 8.8
  9. 35
  10. 86
  11. 23
  12. 27
  13. 7.3
  14. 9.1
  15. 85
  16. 79
  17. 74
  18. 24
  19. 7.4
  20. 5.2
  21. 83
  22. 31
  23. 96
  24. 29
  25. 25
  26. 19
  27. 5.5
  28. 48
  29. 15
  30. 4.6
  31. 78
  32. 9.3
  33. 9.3
  34. 18
  35. 6.6
  36. 5.6
  37. 18
  38. 70
  39. 11
  40. 7.5

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