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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 216 · 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 6306 ÷ 76? (a) 7900 (b) 790 (c) 79
  2. 2.√30 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  3. 3.√96 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 9.8 (d) 10.0
  4. 4.Best estimate of 4056 ÷ 69? (a) 5800 (b) 580 (c) 58
  5. 5.Best estimate of 1292 ÷ 27? (a) 4300 (b) 430 (c) 43
  6. 6.√37 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.2 (d) 6.1
  7. 7.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.1
  8. 8.Best estimate of 2639 ÷ 46? (a) 5300 (b) 53 (c) 530
  9. 9.√27 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.1 (d) 5.2
  10. 10.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  11. 11.Best estimate of 2066 ÷ 83? (a) 2600 (b) 260 (c) 26
  12. 12.Best estimate of 4120 ÷ 57? (a) 6900 (b) 69 (c) 690
  13. 13.√74 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  14. 14.Best estimate of 2198 ÷ 42? (a) 55 (b) 550 (c) 5500
  15. 15.√94 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.7 (d) 9.6
  16. 16.Best estimate of 2950 ÷ 89? (a) 3300 (b) 330 (c) 33
  17. 17.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  18. 18.Best estimate of 1986 ÷ 46? (a) 400 (b) 4000 (c) 40
  19. 19.Best estimate of 4113 ÷ 63? (a) 69 (b) 690 (c) 6900
  20. 20.Best estimate of 2885 ÷ 32? (a) 960 (b) 96 (c) 9600
  21. 21.Best estimate of 1201 ÷ 46? (a) 240 (b) 2400 (c) 24
  22. 22.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  23. 23.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.4
  24. 24.Best estimate of 5202 ÷ 68? (a) 740 (b) 7400 (c) 74
  25. 25.Best estimate of 2123 ÷ 86? (a) 240 (b) 24 (c) 2400
  26. 26.√89 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  27. 27.Best estimate of 814 ÷ 62? (a) 1400 (b) 140 (c) 14
  28. 28.Best estimate of 2331 ÷ 27? (a) 78 (b) 7800 (c) 780
  29. 29.Best estimate of 6284 ÷ 89? (a) 7000 (b) 70 (c) 700
  30. 30.√43 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.6
  31. 31.Best estimate of 400 ÷ 23? (a) 2000 (b) 20 (c) 200
  32. 32.Best estimate of 6280 ÷ 76? (a) 79 (b) 790 (c) 7900
  33. 33.√59 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.8 (d) 7.7
  34. 34.√55 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.4
  35. 35.Best estimate of 2317 ÷ 36? (a) 58 (b) 5800 (c) 580
  36. 36.Best estimate of 1901 ÷ 36? (a) 480 (b) 4800 (c) 48
  37. 37.Best estimate of 754 ÷ 27? (a) 2500 (b) 25 (c) 250
  38. 38.√46 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  39. 39.Best estimate of 1389 ÷ 86? (a) 15 (b) 1500 (c) 150
  40. 40.Best estimate of 2757 ÷ 52? (a) 550 (b) 5500 (c) 55

Answer key

  1. 79
  2. 5.5
  3. 9.8
  4. 58
  5. 43
  6. 6.1
  7. 8.3
  8. 53
  9. 5.2
  10. 9.1
  11. 26
  12. 69
  13. 8.6
  14. 55
  15. 9.7
  16. 33
  17. 5.9
  18. 40
  19. 69
  20. 96
  21. 24
  22. 8.2
  23. 8.1
  24. 74
  25. 24
  26. 9.4
  27. 14
  28. 78
  29. 70
  30. 6.6
  31. 20
  32. 79
  33. 7.7
  34. 7.4
  35. 58
  36. 48
  37. 25
  38. 6.8
  39. 15
  40. 55

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