What percentage of numbers from 1 to 70 have squares that end in the digit 1?	Pick:
A) 1
B) 14
C) 20
D) 21
E) 22
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 numbers = 14.   Required percentage = (14/70 * 100)= 
<gadget id="calculator">(14/70 * 100)</gadget>
<output>20</output>
20%   ANSWER:20
<result>C</result>
What percentage of numbers from 1 to 70 have squares that end in the digit 1?