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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 781 · 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 2146 ÷ 47? (a) 430 (b) 4300 (c) 43
  2. 2.Best estimate of 1707 ÷ 22? (a) 850 (b) 8500 (c) 85
  3. 3.Best estimate of 3385 ÷ 74? (a) 48 (b) 4800 (c) 480
  4. 4.Best estimate of 1935 ÷ 29? (a) 65 (b) 6500 (c) 650
  5. 5.Best estimate of 3313 ÷ 56? (a) 55 (b) 550 (c) 5500
  6. 6.√43 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.5 (d) 6.6
  7. 7.Best estimate of 956 ÷ 24? (a) 48 (b) 4800 (c) 480
  8. 8.√58 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  9. 9.√50 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.1 (d) 7.2
  10. 10.Best estimate of 2137 ÷ 36? (a) 530 (b) 53 (c) 5300
  11. 11.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  12. 12.Best estimate of 2265 ÷ 41? (a) 570 (b) 5700 (c) 57
  13. 13.Best estimate of 1711 ÷ 34? (a) 5700 (b) 57 (c) 570
  14. 14.√86 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4
  15. 15.Best estimate of 770 ÷ 42? (a) 190 (b) 1900 (c) 19
  16. 16.Best estimate of 1084 ÷ 41? (a) 27 (b) 2700 (c) 270
  17. 17.Best estimate of 4140 ÷ 82? (a) 520 (b) 52 (c) 5200
  18. 18.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  19. 19.Best estimate of 5405 ÷ 61? (a) 90 (b) 9000 (c) 900
  20. 20.√63 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  21. 21.Best estimate of 3098 ÷ 36? (a) 77 (b) 7700 (c) 770
  22. 22.Best estimate of 4638 ÷ 69? (a) 6600 (b) 660 (c) 66
  23. 23.√61 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  24. 24.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 10.0
  25. 25.Best estimate of 2865 ÷ 32? (a) 960 (b) 96 (c) 9600
  26. 26.Best estimate of 5343 ÷ 84? (a) 6700 (b) 67 (c) 670
  27. 27.Best estimate of 5896 ÷ 83? (a) 740 (b) 7400 (c) 74
  28. 28.√40 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.5 (d) 6.4
  29. 29.Best estimate of 1941 ÷ 77? (a) 2400 (b) 240 (c) 24
  30. 30.Best estimate of 2896 ÷ 88? (a) 3200 (b) 320 (c) 32
  31. 31.Best estimate of 1490 ÷ 28? (a) 5000 (b) 50 (c) 500
  32. 32.√66 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 8.1
  33. 33.Best estimate of 1126 ÷ 23? (a) 56 (b) 5600 (c) 560
  34. 34.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 10.0
  35. 35.√83 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  36. 36.Best estimate of 1398 ÷ 64? (a) 23 (b) 230 (c) 2300
  37. 37.Best estimate of 5656 ÷ 73? (a) 81 (b) 8100 (c) 810
  38. 38.√80 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  39. 39.√65 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  40. 40.√32 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.5 (d) 5.7

Answer key

  1. 43
  2. 85
  3. 48
  4. 65
  5. 55
  6. 6.6
  7. 48
  8. 7.6
  9. 7.1
  10. 53
  11. 7.4
  12. 57
  13. 57
  14. 9.3
  15. 19
  16. 27
  17. 52
  18. 6.8
  19. 90
  20. 7.9
  21. 77
  22. 66
  23. 7.8
  24. 9.9
  25. 96
  26. 67
  27. 74
  28. 6.3
  29. 24
  30. 32
  31. 50
  32. 8.1
  33. 56
  34. 9.7
  35. 9.1
  36. 23
  37. 81
  38. 8.9
  39. 8.1
  40. 5.7

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