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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 711 · 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 3535 ÷ 58? (a) 5900 (b) 590 (c) 59
  2. 2.Best estimate of 1113 ÷ 26? (a) 370 (b) 37 (c) 3700
  3. 3.Best estimate of 3901 ÷ 82? (a) 4900 (b) 49 (c) 490
  4. 4.√79 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.9
  5. 5.√96 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.9 (d) 9.8
  6. 6.Best estimate of 802 ÷ 21? (a) 4000 (b) 40 (c) 400
  7. 7.Best estimate of 6636 ÷ 87? (a) 740 (b) 7400 (c) 74
  8. 8.Best estimate of 6316 ÷ 84? (a) 7900 (b) 79 (c) 790
  9. 9.√89 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  10. 10.Best estimate of 869 ÷ 64? (a) 140 (b) 14 (c) 1400
  11. 11.√44 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  12. 12.√69 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.3
  13. 13.Best estimate of 1428 ÷ 32? (a) 480 (b) 48 (c) 4800
  14. 14.Best estimate of 2036 ÷ 48? (a) 41 (b) 4100 (c) 410
  15. 15.√27 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.1 (d) 4.9
  16. 16.√50 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 6.8
  17. 17.Best estimate of 322 ÷ 23? (a) 16 (b) 160 (c) 1600
  18. 18.√78 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 9.0
  19. 19.√34 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.8
  20. 20.√43 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  21. 21.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  22. 22.Best estimate of 1362 ÷ 36? (a) 340 (b) 3400 (c) 34
  23. 23.Best estimate of 1504 ÷ 28? (a) 5000 (b) 500 (c) 50
  24. 24.Best estimate of 1666 ÷ 52? (a) 3300 (b) 33 (c) 330
  25. 25.√98 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 10.0 (d) 9.9
  26. 26.√22 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.8 (d) 4.7
  27. 27.Best estimate of 1424 ÷ 31? (a) 4700 (b) 470 (c) 47
  28. 28.√87 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  29. 29.√42 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  30. 30.Best estimate of 805 ÷ 27? (a) 270 (b) 2700 (c) 27
  31. 31.Best estimate of 2253 ÷ 29? (a) 750 (b) 75 (c) 7500
  32. 32.Best estimate of 1989 ÷ 59? (a) 33 (b) 330 (c) 3300
  33. 33.√47 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 7.0 (d) 6.8
  34. 34.Best estimate of 2840 ÷ 86? (a) 320 (b) 32 (c) 3200
  35. 35.Best estimate of 941 ÷ 58? (a) 1600 (b) 16 (c) 160
  36. 36.Best estimate of 5384 ÷ 82? (a) 670 (b) 6700 (c) 67
  37. 37.Best estimate of 1930 ÷ 46? (a) 390 (b) 39 (c) 3900
  38. 38.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  39. 39.√55 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.6 (d) 7.5
  40. 40.√41 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5

Answer key

  1. 59
  2. 37
  3. 49
  4. 8.9
  5. 9.8
  6. 40
  7. 74
  8. 79
  9. 9.4
  10. 14
  11. 6.6
  12. 8.3
  13. 48
  14. 41
  15. 5.2
  16. 7.1
  17. 16
  18. 8.8
  19. 5.8
  20. 6.6
  21. 9.5
  22. 34
  23. 50
  24. 33
  25. 9.9
  26. 4.7
  27. 47
  28. 9.3
  29. 6.5
  30. 27
  31. 75
  32. 33
  33. 6.9
  34. 32
  35. 16
  36. 67
  37. 39
  38. 4.5
  39. 7.4
  40. 6.4

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