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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 332 · 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.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  2. 2.√34 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.8 (d) 5.7
  3. 3.√50 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 6.8 (d) 7.0
  4. 4.√21 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 4.6
  5. 5.√67 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  6. 6.√69 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.3 (d) 8.5
  7. 7.√58 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 7.6
  8. 8.Best estimate of 2754 ÷ 67? (a) 390 (b) 3900 (c) 39
  9. 9.Best estimate of 387 ÷ 21? (a) 1900 (b) 190 (c) 19
  10. 10.Best estimate of 748 ÷ 33? (a) 2500 (b) 25 (c) 250
  11. 11.Best estimate of 2276 ÷ 26? (a) 760 (b) 7600 (c) 76
  12. 12.Best estimate of 2443 ÷ 79? (a) 310 (b) 31 (c) 3100
  13. 13.Best estimate of 3742 ÷ 83? (a) 470 (b) 47 (c) 4700
  14. 14.√44 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.7 (d) 6.8
  15. 15.Best estimate of 2196 ÷ 79? (a) 270 (b) 2700 (c) 27
  16. 16.√43 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  17. 17.Best estimate of 5632 ÷ 86? (a) 63 (b) 6300 (c) 630
  18. 18.Best estimate of 2341 ÷ 42? (a) 59 (b) 590 (c) 5900
  19. 19.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 10.0
  20. 20.Best estimate of 5074 ÷ 56? (a) 850 (b) 8500 (c) 85
  21. 21.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 7.0
  22. 22.Best estimate of 1023 ÷ 63? (a) 1700 (b) 170 (c) 17
  23. 23.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.3 (d) 5.2
  24. 24.Best estimate of 4132 ÷ 89? (a) 460 (b) 4600 (c) 46
  25. 25.Best estimate of 1969 ÷ 22? (a) 980 (b) 98 (c) 9800
  26. 26.Best estimate of 3898 ÷ 66? (a) 5600 (b) 56 (c) 560
  27. 27.√96 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  28. 28.√87 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  29. 29.√74 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  30. 30.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 8.1
  31. 31.√75 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  32. 32.Best estimate of 1170 ÷ 34? (a) 39 (b) 3900 (c) 390
  33. 33.√82 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  34. 34.Best estimate of 500 ÷ 37? (a) 1300 (b) 130 (c) 13
  35. 35.Best estimate of 984 ÷ 21? (a) 490 (b) 49 (c) 4900
  36. 36.Best estimate of 1026 ÷ 47? (a) 21 (b) 210 (c) 2100
  37. 37.Best estimate of 2140 ÷ 53? (a) 43 (b) 430 (c) 4300
  38. 38.√76 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  39. 39.√20 to 1 decimal place? (a) 4.6 (b) 4.3 (c) 4.5 (d) 4.4
  40. 40.Best estimate of 678 ÷ 51? (a) 1400 (b) 140 (c) 14

Answer key

  1. 5.5
  2. 5.8
  3. 7.1
  4. 4.6
  5. 8.2
  6. 8.3
  7. 7.6
  8. 39
  9. 19
  10. 25
  11. 76
  12. 31
  13. 47
  14. 6.6
  15. 27
  16. 6.6
  17. 63
  18. 59
  19. 9.9
  20. 85
  21. 6.9
  22. 17
  23. 5.1
  24. 46
  25. 98
  26. 56
  27. 9.8
  28. 9.3
  29. 8.6
  30. 7.8
  31. 8.7
  32. 39
  33. 9.1
  34. 13
  35. 49
  36. 21
  37. 43
  38. 8.7
  39. 4.5
  40. 14

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