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### Discussion :: Percentage

1. What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?

2.  A. 1 B. 14 C. 20 D. 21

Explanation :

Clearly, the numbers which have 1 or 9 in the unit's digit, have squares that end in the digit 1.

Such numbers from 1 to 70 are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.

Number of such number =14

Required Percentage = $$[ \frac { 14} { 70} \times100]%=20%$$% = 20%

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