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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 255 · 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.√35 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.8 (d) 5.9
  2. 2.√61 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.9
  3. 3.√58 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  4. 4.Best estimate of 3814 ÷ 69? (a) 54 (b) 5400 (c) 540
  5. 5.Best estimate of 8419 ÷ 89? (a) 940 (b) 9400 (c) 94
  6. 6.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 6.1
  7. 7.Best estimate of 4716 ÷ 63? (a) 7900 (b) 79 (c) 790
  8. 8.Best estimate of 3570 ÷ 88? (a) 400 (b) 40 (c) 4000
  9. 9.Best estimate of 525 ÷ 41? (a) 13 (b) 1300 (c) 130
  10. 10.Best estimate of 5290 ÷ 66? (a) 7600 (b) 760 (c) 76
  11. 11.√52 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.0
  12. 12.Best estimate of 1970 ÷ 36? (a) 490 (b) 49 (c) 4900
  13. 13.Best estimate of 852 ÷ 42? (a) 2100 (b) 21 (c) 210
  14. 14.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  15. 15.Best estimate of 1136 ÷ 84? (a) 1400 (b) 14 (c) 140
  16. 16.√45 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.8 (d) 6.7
  17. 17.Best estimate of 841 ÷ 36? (a) 210 (b) 2100 (c) 21
  18. 18.Best estimate of 1614 ÷ 23? (a) 810 (b) 8100 (c) 81
  19. 19.√79 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 8.6
  20. 20.Best estimate of 6926 ÷ 79? (a) 870 (b) 8700 (c) 87
  21. 21.√85 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.1 (d) 9.3
  22. 22.√40 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.3 (d) 6.2
  23. 23.Best estimate of 2435 ÷ 58? (a) 41 (b) 410 (c) 4100
  24. 24.Best estimate of 941 ÷ 38? (a) 240 (b) 2400 (c) 24
  25. 25.Best estimate of 3747 ÷ 57? (a) 620 (b) 6200 (c) 62
  26. 26.Best estimate of 1460 ÷ 84? (a) 1800 (b) 180 (c) 18
  27. 27.√67 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  28. 28.Best estimate of 1934 ÷ 26? (a) 640 (b) 64 (c) 6400
  29. 29.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.4
  30. 30.Best estimate of 2574 ÷ 44? (a) 64 (b) 6400 (c) 640
  31. 31.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 9.9 (d) 10.0
  32. 32.Best estimate of 5207 ÷ 81? (a) 650 (b) 6500 (c) 65
  33. 33.Best estimate of 2727 ÷ 87? (a) 300 (b) 3000 (c) 30
  34. 34.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 7.3
  35. 35.Best estimate of 2738 ÷ 31? (a) 91 (b) 9100 (c) 910
  36. 36.Best estimate of 1036 ÷ 24? (a) 52 (b) 520 (c) 5200
  37. 37.Best estimate of 2097 ÷ 27? (a) 700 (b) 7000 (c) 70
  38. 38.Best estimate of 936 ÷ 69? (a) 13 (b) 1300 (c) 130
  39. 39.√65 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  40. 40.√94 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.8 (d) 9.9

Answer key

  1. 5.9
  2. 7.8
  3. 7.6
  4. 54
  5. 94
  6. 6.1
  7. 79
  8. 40
  9. 13
  10. 76
  11. 7.2
  12. 49
  13. 21
  14. 7.9
  15. 14
  16. 6.7
  17. 21
  18. 81
  19. 8.9
  20. 87
  21. 9.2
  22. 6.3
  23. 41
  24. 24
  25. 62
  26. 18
  27. 8.2
  28. 64
  29. 4.7
  30. 64
  31. 9.9
  32. 65
  33. 30
  34. 7.1
  35. 91
  36. 52
  37. 70
  38. 13
  39. 8.1
  40. 9.7

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