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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 791 · 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.√84 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  2. 2.Best estimate of 2696 ÷ 34? (a) 9000 (b) 900 (c) 90
  3. 3.Best estimate of 4207 ÷ 57? (a) 700 (b) 7000 (c) 70
  4. 4.√85 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.2 (d) 9.1
  5. 5.Best estimate of 4711 ÷ 56? (a) 7900 (b) 790 (c) 79
  6. 6.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.6 (d) 5.8
  7. 7.√32 to 1 decimal place? (a) 5.7 (b) 6.0 (c) 5.9 (d) 5.8
  8. 8.√50 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  9. 9.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 5.3
  10. 10.Best estimate of 3389 ÷ 42? (a) 850 (b) 85 (c) 8500
  11. 11.Best estimate of 6250 ÷ 71? (a) 8900 (b) 89 (c) 890
  12. 12.Best estimate of 3170 ÷ 34? (a) 10600 (b) 106 (c) 1060
  13. 13.Best estimate of 6796 ÷ 77? (a) 850 (b) 8500 (c) 85
  14. 14.Best estimate of 1481 ÷ 34? (a) 490 (b) 49 (c) 4900
  15. 15.Best estimate of 2861 ÷ 32? (a) 950 (b) 95 (c) 9500
  16. 16.Best estimate of 2620 ÷ 69? (a) 3700 (b) 370 (c) 37
  17. 17.Best estimate of 2734 ÷ 62? (a) 460 (b) 46 (c) 4600
  18. 18.Best estimate of 533 ÷ 44? (a) 130 (b) 1300 (c) 13
  19. 19.Best estimate of 976 ÷ 24? (a) 49 (b) 490 (c) 4900
  20. 20.Best estimate of 3735 ÷ 69? (a) 5300 (b) 53 (c) 530
  21. 21.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  22. 22.Best estimate of 4739 ÷ 57? (a) 79 (b) 790 (c) 7900
  23. 23.Best estimate of 6321 ÷ 66? (a) 90 (b) 9000 (c) 900
  24. 24.Best estimate of 2622 ÷ 33? (a) 870 (b) 8700 (c) 87
  25. 25.Best estimate of 2860 ÷ 79? (a) 36 (b) 3600 (c) 360
  26. 26.√72 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.4 (d) 8.5
  27. 27.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  28. 28.Best estimate of 4138 ÷ 72? (a) 590 (b) 5900 (c) 59
  29. 29.Best estimate of 1935 ÷ 24? (a) 97 (b) 970 (c) 9700
  30. 30.Best estimate of 701 ÷ 44? (a) 1800 (b) 18 (c) 180
  31. 31.Best estimate of 4749 ÷ 74? (a) 680 (b) 6800 (c) 68
  32. 32.√89 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.2 (d) 9.4
  33. 33.√35 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  34. 34.√66 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 7.9 (d) 8.1
  35. 35.Best estimate of 5037 ÷ 86? (a) 5600 (b) 56 (c) 560
  36. 36.Best estimate of 1864 ÷ 67? (a) 270 (b) 2700 (c) 27
  37. 37.√69 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.3
  38. 38.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.9 (d) 9.8
  39. 39.Best estimate of 5992 ÷ 66? (a) 860 (b) 8600 (c) 86
  40. 40.√56 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3

Answer key

  1. 9.2
  2. 90
  3. 70
  4. 9.2
  5. 79
  6. 5.8
  7. 5.7
  8. 7.1
  9. 5.1
  10. 85
  11. 89
  12. 106
  13. 85
  14. 49
  15. 95
  16. 37
  17. 46
  18. 13
  19. 49
  20. 53
  21. 7.4
  22. 79
  23. 90
  24. 87
  25. 36
  26. 8.5
  27. 4.9
  28. 59
  29. 97
  30. 18
  31. 68
  32. 9.4
  33. 5.9
  34. 8.1
  35. 56
  36. 27
  37. 8.3
  38. 9.9
  39. 86
  40. 7.5

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