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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 258 · 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 1806 ÷ 44? (a) 450 (b) 45 (c) 4500
  2. 2.Best estimate of 3349 ÷ 46? (a) 670 (b) 6700 (c) 67
  3. 3.Best estimate of 1134 ÷ 69? (a) 16 (b) 1600 (c) 160
  4. 4.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  5. 5.Best estimate of 2422 ÷ 46? (a) 4800 (b) 480 (c) 48
  6. 6.Best estimate of 2028 ÷ 28? (a) 6800 (b) 680 (c) 68
  7. 7.√62 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.9 (d) 7.8
  8. 8.Best estimate of 1008 ÷ 21? (a) 5000 (b) 50 (c) 500
  9. 9.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  10. 10.√86 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  11. 11.√78 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  12. 12.Best estimate of 2730 ÷ 81? (a) 340 (b) 3400 (c) 34
  13. 13.Best estimate of 943 ÷ 32? (a) 310 (b) 3100 (c) 31
  14. 14.Best estimate of 2276 ÷ 86? (a) 250 (b) 2500 (c) 25
  15. 15.√50 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 6.8
  16. 16.Best estimate of 1538 ÷ 42? (a) 3800 (b) 38 (c) 380
  17. 17.√41 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.4 (d) 6.3
  18. 18.√67 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.0 (d) 8.2
  19. 19.Best estimate of 1217 ÷ 27? (a) 4100 (b) 41 (c) 410
  20. 20.Best estimate of 836 ÷ 26? (a) 28 (b) 280 (c) 2800
  21. 21.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 6.2
  22. 22.Best estimate of 2484 ÷ 54? (a) 50 (b) 5000 (c) 500
  23. 23.√28 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  24. 24.Best estimate of 4588 ÷ 69? (a) 660 (b) 6600 (c) 66
  25. 25.√51 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  26. 26.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  27. 27.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  28. 28.Best estimate of 2354 ÷ 69? (a) 3400 (b) 34 (c) 340
  29. 29.Best estimate of 779 ÷ 29? (a) 2600 (b) 260 (c) 26
  30. 30.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  31. 31.Best estimate of 3913 ÷ 43? (a) 98 (b) 980 (c) 9800
  32. 32.√22 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  33. 33.Best estimate of 5815 ÷ 66? (a) 83 (b) 8300 (c) 830
  34. 34.Best estimate of 7122 ÷ 89? (a) 790 (b) 79 (c) 7900
  35. 35.Best estimate of 1121 ÷ 48? (a) 2200 (b) 220 (c) 22
  36. 36.Best estimate of 2827 ÷ 58? (a) 470 (b) 4700 (c) 47
  37. 37.Best estimate of 1998 ÷ 67? (a) 2900 (b) 290 (c) 29
  38. 38.Best estimate of 3896 ÷ 74? (a) 560 (b) 5600 (c) 56
  39. 39.Best estimate of 3388 ÷ 79? (a) 42 (b) 420 (c) 4200
  40. 40.√66 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1

Answer key

  1. 45
  2. 67
  3. 16
  4. 9.1
  5. 48
  6. 68
  7. 7.9
  8. 50
  9. 7.6
  10. 9.3
  11. 8.8
  12. 34
  13. 31
  14. 25
  15. 7.1
  16. 38
  17. 6.4
  18. 8.2
  19. 41
  20. 28
  21. 6.1
  22. 50
  23. 5.3
  24. 66
  25. 7.1
  26. 5.1
  27. 5.7
  28. 34
  29. 26
  30. 9.9
  31. 98
  32. 4.7
  33. 83
  34. 79
  35. 22
  36. 47
  37. 29
  38. 56
  39. 42
  40. 8.1

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