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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 433 · 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 3895 ÷ 57? (a) 650 (b) 6500 (c) 65
  2. 2.Best estimate of 2881 ÷ 33? (a) 96 (b) 960 (c) 9600
  3. 3.√35 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.8 (d) 5.6
  4. 4.Best estimate of 2914 ÷ 34? (a) 970 (b) 9700 (c) 97
  5. 5.√66 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 8.0 (d) 7.8
  6. 6.√83 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  7. 7.Best estimate of 3248 ÷ 87? (a) 360 (b) 36 (c) 3600
  8. 8.Best estimate of 868 ÷ 53? (a) 170 (b) 17 (c) 1700
  9. 9.Best estimate of 406 ÷ 32? (a) 14 (b) 1400 (c) 140
  10. 10.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.4
  11. 11.Best estimate of 1017 ÷ 22? (a) 5100 (b) 51 (c) 510
  12. 12.Best estimate of 1898 ÷ 79? (a) 2400 (b) 24 (c) 240
  13. 13.Best estimate of 2035 ÷ 39? (a) 510 (b) 5100 (c) 51
  14. 14.Best estimate of 1167 ÷ 66? (a) 17 (b) 170 (c) 1700
  15. 15.√50 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.0 (d) 7.2
  16. 16.Best estimate of 1287 ÷ 54? (a) 26 (b) 260 (c) 2600
  17. 17.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.5
  18. 18.Best estimate of 2248 ÷ 42? (a) 560 (b) 5600 (c) 56
  19. 19.Best estimate of 4869 ÷ 52? (a) 97 (b) 970 (c) 9700
  20. 20.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.4
  21. 21.Best estimate of 3729 ÷ 42? (a) 93 (b) 930 (c) 9300
  22. 22.√96 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 9.9 (d) 10.0
  23. 23.Best estimate of 1640 ÷ 27? (a) 5500 (b) 55 (c) 550
  24. 24.√80 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 9.0
  25. 25.√78 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 9.0
  26. 26.Best estimate of 1898 ÷ 71? (a) 270 (b) 2700 (c) 27
  27. 27.Best estimate of 1049 ÷ 76? (a) 1300 (b) 13 (c) 130
  28. 28.Best estimate of 1133 ÷ 22? (a) 570 (b) 5700 (c) 57
  29. 29.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.9 (d) 4.7
  30. 30.Best estimate of 2446 ÷ 36? (a) 61 (b) 610 (c) 6100
  31. 31.Best estimate of 2544 ÷ 79? (a) 32 (b) 3200 (c) 320
  32. 32.Best estimate of 1756 ÷ 32? (a) 59 (b) 5900 (c) 590
  33. 33.Best estimate of 877 ÷ 42? (a) 22 (b) 2200 (c) 220
  34. 34.Best estimate of 880 ÷ 72? (a) 13 (b) 130 (c) 1300
  35. 35.√37 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  36. 36.Best estimate of 2794 ÷ 52? (a) 560 (b) 5600 (c) 56
  37. 37.Best estimate of 2293 ÷ 27? (a) 760 (b) 76 (c) 7600
  38. 38.Best estimate of 1647 ÷ 77? (a) 2100 (b) 21 (c) 210
  39. 39.Best estimate of 5486 ÷ 62? (a) 910 (b) 9100 (c) 91
  40. 40.√21 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.8

Answer key

  1. 65
  2. 96
  3. 5.9
  4. 97
  5. 8.1
  6. 9.1
  7. 36
  8. 17
  9. 14
  10. 5.6
  11. 51
  12. 24
  13. 51
  14. 17
  15. 7.1
  16. 26
  17. 8.6
  18. 56
  19. 97
  20. 9.6
  21. 93
  22. 9.8
  23. 55
  24. 8.9
  25. 8.8
  26. 27
  27. 13
  28. 57
  29. 4.9
  30. 61
  31. 32
  32. 59
  33. 22
  34. 13
  35. 6.1
  36. 56
  37. 76
  38. 21
  39. 91
  40. 4.6

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