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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 897 · 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.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  2. 2.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 6.9 (d) 7.1
  3. 3.Best estimate of 1179 ÷ 51? (a) 240 (b) 24 (c) 2400
  4. 4.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.8
  5. 5.Best estimate of 6051 ÷ 76? (a) 7600 (b) 760 (c) 76
  6. 6.Best estimate of 1739 ÷ 57? (a) 29 (b) 290 (c) 2900
  7. 7.√69 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3
  8. 8.√45 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  9. 9.Best estimate of 1561 ÷ 54? (a) 310 (b) 31 (c) 3100
  10. 10.Best estimate of 4007 ÷ 61? (a) 67 (b) 6700 (c) 670
  11. 11.√75 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  12. 12.Best estimate of 4332 ÷ 56? (a) 7200 (b) 720 (c) 72
  13. 13.Best estimate of 2148 ÷ 31? (a) 72 (b) 7200 (c) 720
  14. 14.√20 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.6 (d) 4.4
  15. 15.Best estimate of 4079 ÷ 87? (a) 4500 (b) 45 (c) 450
  16. 16.Best estimate of 5804 ÷ 87? (a) 640 (b) 6400 (c) 64
  17. 17.√88 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4
  18. 18.Best estimate of 4957 ÷ 56? (a) 8300 (b) 83 (c) 830
  19. 19.Best estimate of 806 ÷ 42? (a) 2000 (b) 20 (c) 200
  20. 20.√52 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.4 (d) 7.2
  21. 21.√86 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  22. 22.Best estimate of 3254 ÷ 67? (a) 4600 (b) 460 (c) 46
  23. 23.Best estimate of 2927 ÷ 34? (a) 980 (b) 9800 (c) 98
  24. 24.Best estimate of 2486 ÷ 82? (a) 3100 (b) 310 (c) 31
  25. 25.Best estimate of 3928 ÷ 71? (a) 56 (b) 560 (c) 5600
  26. 26.Best estimate of 807 ÷ 27? (a) 270 (b) 2700 (c) 27
  27. 27.Best estimate of 728 ÷ 56? (a) 120 (b) 1200 (c) 12
  28. 28.Best estimate of 1618 ÷ 42? (a) 40 (b) 4000 (c) 400
  29. 29.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  30. 30.Best estimate of 5122 ÷ 82? (a) 640 (b) 6400 (c) 64
  31. 31.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  32. 32.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 8.2
  33. 33.Best estimate of 1704 ÷ 66? (a) 24 (b) 2400 (c) 240
  34. 34.Best estimate of 1597 ÷ 71? (a) 23 (b) 230 (c) 2300
  35. 35.√28 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.6
  36. 36.Best estimate of 1651 ÷ 24? (a) 83 (b) 8300 (c) 830
  37. 37.Best estimate of 5508 ÷ 58? (a) 92 (b) 920 (c) 9200
  38. 38.Best estimate of 1284 ÷ 36? (a) 320 (b) 3200 (c) 32
  39. 39.√38 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  40. 40.Best estimate of 611 ÷ 41? (a) 150 (b) 1500 (c) 15

Answer key

  1. 7.9
  2. 7.1
  3. 24
  4. 7.6
  5. 76
  6. 29
  7. 8.3
  8. 6.7
  9. 31
  10. 67
  11. 8.7
  12. 72
  13. 72
  14. 4.5
  15. 45
  16. 64
  17. 9.4
  18. 83
  19. 20
  20. 7.2
  21. 9.3
  22. 46
  23. 98
  24. 31
  25. 56
  26. 27
  27. 12
  28. 40
  29. 6.1
  30. 64
  31. 8.1
  32. 8.1
  33. 24
  34. 23
  35. 5.3
  36. 83
  37. 92
  38. 32
  39. 6.2
  40. 15

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