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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 531 · 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.√27 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.2 (d) 5.0
  2. 2.√69 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.3 (d) 8.6
  3. 3.Best estimate of 7266 ÷ 78? (a) 910 (b) 91 (c) 9100
  4. 4.√20 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.4 (d) 4.5
  5. 5.√72 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  6. 6.Best estimate of 824 ÷ 21? (a) 41 (b) 4100 (c) 410
  7. 7.Best estimate of 677 ÷ 26? (a) 23 (b) 2300 (c) 230
  8. 8.Best estimate of 935 ÷ 34? (a) 3100 (b) 31 (c) 310
  9. 9.Best estimate of 2030 ÷ 46? (a) 4100 (b) 41 (c) 410
  10. 10.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.7 (d) 5.9
  11. 11.√45 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.9
  12. 12.Best estimate of 3365 ÷ 43? (a) 840 (b) 84 (c) 8400
  13. 13.Best estimate of 810 ÷ 41? (a) 200 (b) 2000 (c) 20
  14. 14.Best estimate of 4527 ÷ 82? (a) 57 (b) 570 (c) 5700
  15. 15.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.8
  16. 16.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 7.6
  17. 17.Best estimate of 7732 ÷ 89? (a) 8600 (b) 860 (c) 86
  18. 18.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.7 (d) 4.9
  19. 19.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  20. 20.Best estimate of 3087 ÷ 42? (a) 77 (b) 770 (c) 7700
  21. 21.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 7.9 (d) 8.0
  22. 22.√38 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 5.9
  23. 23.√85 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.1 (d) 9.0
  24. 24.Best estimate of 1611 ÷ 74? (a) 2300 (b) 23 (c) 230
  25. 25.Best estimate of 1528 ÷ 87? (a) 17 (b) 1700 (c) 170
  26. 26.Best estimate of 3959 ÷ 84? (a) 4900 (b) 49 (c) 490
  27. 27.Best estimate of 5015 ÷ 68? (a) 72 (b) 720 (c) 7200
  28. 28.√62 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 8.1
  29. 29.Best estimate of 1592 ÷ 89? (a) 18 (b) 1800 (c) 180
  30. 30.Best estimate of 1442 ÷ 32? (a) 4800 (b) 480 (c) 48
  31. 31.√89 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  32. 32.Best estimate of 1363 ÷ 28? (a) 4500 (b) 45 (c) 450
  33. 33.Best estimate of 3540 ÷ 66? (a) 51 (b) 510 (c) 5100
  34. 34.Best estimate of 4271 ÷ 52? (a) 850 (b) 85 (c) 8500
  35. 35.√67 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.5 (d) 8.4
  36. 36.Best estimate of 4183 ÷ 71? (a) 60 (b) 6000 (c) 600
  37. 37.Best estimate of 4485 ÷ 64? (a) 7500 (b) 75 (c) 750
  38. 38.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  39. 39.Best estimate of 5853 ÷ 73? (a) 8400 (b) 84 (c) 840
  40. 40.Best estimate of 5015 ÷ 54? (a) 10000 (b) 1000 (c) 100

Answer key

  1. 5.2
  2. 8.3
  3. 91
  4. 4.5
  5. 8.5
  6. 41
  7. 23
  8. 31
  9. 41
  10. 5.8
  11. 6.7
  12. 84
  13. 20
  14. 57
  15. 7.5
  16. 7.8
  17. 86
  18. 4.9
  19. 7.4
  20. 77
  21. 8.1
  22. 6.2
  23. 9.2
  24. 23
  25. 17
  26. 49
  27. 72
  28. 7.9
  29. 18
  30. 48
  31. 9.4
  32. 45
  33. 51
  34. 85
  35. 8.2
  36. 60
  37. 75
  38. 5.5
  39. 84
  40. 100

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