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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 234 · 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 1215 ÷ 42? (a) 30 (b) 3000 (c) 300
  2. 2.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.1 (d) 6.2
  3. 3.√43 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.3
  4. 4.√61 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  5. 5.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3
  6. 6.√72 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  7. 7.Best estimate of 6296 ÷ 76? (a) 790 (b) 7900 (c) 79
  8. 8.Best estimate of 1527 ÷ 39? (a) 380 (b) 38 (c) 3800
  9. 9.Best estimate of 1492 ÷ 23? (a) 7500 (b) 750 (c) 75
  10. 10.Best estimate of 1328 ÷ 31? (a) 4400 (b) 44 (c) 440
  11. 11.Best estimate of 2675 ÷ 34? (a) 89 (b) 890 (c) 8900
  12. 12.Best estimate of 3867 ÷ 43? (a) 970 (b) 97 (c) 9700
  13. 13.Best estimate of 3893 ÷ 53? (a) 7800 (b) 780 (c) 78
  14. 14.Best estimate of 1898 ÷ 83? (a) 240 (b) 24 (c) 2400
  15. 15.Best estimate of 2677 ÷ 33? (a) 89 (b) 890 (c) 8900
  16. 16.Best estimate of 4187 ÷ 79? (a) 5200 (b) 520 (c) 52
  17. 17.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  18. 18.Best estimate of 984 ÷ 57? (a) 1600 (b) 160 (c) 16
  19. 19.Best estimate of 2350 ÷ 43? (a) 590 (b) 5900 (c) 59
  20. 20.√34 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 5.8
  21. 21.√50 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.1
  22. 22.Best estimate of 7142 ÷ 88? (a) 790 (b) 7900 (c) 79
  23. 23.Best estimate of 1672 ÷ 26? (a) 5600 (b) 560 (c) 56
  24. 24.√96 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  25. 25.Best estimate of 3498 ÷ 72? (a) 50 (b) 5000 (c) 500
  26. 26.√89 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  27. 27.Best estimate of 964 ÷ 68? (a) 1400 (b) 140 (c) 14
  28. 28.Best estimate of 5353 ÷ 62? (a) 8900 (b) 89 (c) 890
  29. 29.Best estimate of 5375 ÷ 82? (a) 67 (b) 670 (c) 6700
  30. 30.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  31. 31.Best estimate of 3688 ÷ 58? (a) 6100 (b) 610 (c) 61
  32. 32.Best estimate of 6867 ÷ 76? (a) 8600 (b) 860 (c) 86
  33. 33.√90 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.4 (d) 9.6
  34. 34.Best estimate of 7347 ÷ 89? (a) 82 (b) 820 (c) 8200
  35. 35.√83 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.0 (d) 8.8
  36. 36.Best estimate of 1528 ÷ 82? (a) 1900 (b) 19 (c) 190
  37. 37.Best estimate of 669 ÷ 27? (a) 2200 (b) 220 (c) 22
  38. 38.Best estimate of 4707 ÷ 52? (a) 940 (b) 9400 (c) 94
  39. 39.√29 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  40. 40.Best estimate of 2978 ÷ 81? (a) 370 (b) 3700 (c) 37

Answer key

  1. 30
  2. 6.3
  3. 6.6
  4. 7.8
  5. 6.1
  6. 8.5
  7. 79
  8. 38
  9. 75
  10. 44
  11. 89
  12. 97
  13. 78
  14. 24
  15. 89
  16. 52
  17. 7.6
  18. 16
  19. 59
  20. 5.8
  21. 7.1
  22. 79
  23. 56
  24. 9.8
  25. 50
  26. 9.4
  27. 14
  28. 89
  29. 67
  30. 9.3
  31. 61
  32. 86
  33. 9.5
  34. 82
  35. 9.1
  36. 19
  37. 22
  38. 94
  39. 5.4
  40. 37

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