What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?	Pick one
A) 10 % B) 30 % C) 20 % D) 70 % E) 45 %

Rationale: d 20 % 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 = ( 14 x 100 / 70 ) % = 20 % .
Answer: C