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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 542 · 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 1055 ÷ 77? (a) 1300 (b) 130 (c) 13
  2. 2.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.5
  3. 3.Best estimate of 2004 ÷ 26? (a) 67 (b) 670 (c) 6700
  4. 4.Best estimate of 5122 ÷ 69? (a) 7300 (b) 730 (c) 73
  5. 5.Best estimate of 1929 ÷ 24? (a) 9600 (b) 960 (c) 96
  6. 6.√44 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.6 (d) 6.7
  7. 7.Best estimate of 1066 ÷ 34? (a) 36 (b) 360 (c) 3600
  8. 8.√83 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.3 (d) 9.2
  9. 9.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  10. 10.Best estimate of 893 ÷ 49? (a) 18 (b) 180 (c) 1800
  11. 11.Best estimate of 782 ÷ 28? (a) 26 (b) 2600 (c) 260
  12. 12.Best estimate of 4121 ÷ 64? (a) 6900 (b) 690 (c) 69
  13. 13.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.4
  14. 14.√35 to 1 decimal place? (a) 6.2 (b) 5.9 (c) 6.1 (d) 6.0
  15. 15.Best estimate of 1779 ÷ 26? (a) 59 (b) 5900 (c) 590
  16. 16.Best estimate of 3635 ÷ 43? (a) 91 (b) 9100 (c) 910
  17. 17.√75 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.8 (d) 8.7
  18. 18.√85 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  19. 19.√86 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  20. 20.√46 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.7 (d) 6.8
  21. 21.Best estimate of 2551 ÷ 31? (a) 8500 (b) 850 (c) 85
  22. 22.√74 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.3 (d) 8.6
  23. 23.Best estimate of 1474 ÷ 24? (a) 740 (b) 7400 (c) 74
  24. 24.Best estimate of 7461 ÷ 86? (a) 830 (b) 8300 (c) 83
  25. 25.Best estimate of 1625 ÷ 36? (a) 41 (b) 4100 (c) 410
  26. 26.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.5 (d) 5.7
  27. 27.Best estimate of 2048 ÷ 88? (a) 23 (b) 230 (c) 2300
  28. 28.Best estimate of 1367 ÷ 44? (a) 340 (b) 3400 (c) 34
  29. 29.Best estimate of 907 ÷ 39? (a) 230 (b) 2300 (c) 23
  30. 30.Best estimate of 681 ÷ 37? (a) 17 (b) 170 (c) 1700
  31. 31.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  32. 32.Best estimate of 3318 ÷ 46? (a) 6600 (b) 660 (c) 66
  33. 33.Best estimate of 1150 ÷ 59? (a) 190 (b) 19 (c) 1900
  34. 34.Best estimate of 5400 ÷ 63? (a) 90 (b) 900 (c) 9000
  35. 35.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.3
  36. 36.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  37. 37.Best estimate of 3601 ÷ 44? (a) 900 (b) 90 (c) 9000
  38. 38.Best estimate of 956 ÷ 63? (a) 1600 (b) 16 (c) 160
  39. 39.Best estimate of 1426 ÷ 49? (a) 29 (b) 2900 (c) 290
  40. 40.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.1 (d) 8.0

Answer key

  1. 13
  2. 7.2
  3. 67
  4. 73
  5. 96
  6. 6.6
  7. 36
  8. 9.1
  9. 7.6
  10. 18
  11. 26
  12. 69
  13. 5.1
  14. 5.9
  15. 59
  16. 91
  17. 8.7
  18. 9.2
  19. 9.3
  20. 6.8
  21. 85
  22. 8.6
  23. 74
  24. 83
  25. 41
  26. 5.8
  27. 23
  28. 34
  29. 23
  30. 17
  31. 6.6
  32. 66
  33. 19
  34. 90
  35. 6.3
  36. 9.8
  37. 90
  38. 16
  39. 29
  40. 7.8

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