What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?
A. 1%
B. 14%
C. 20%
D. 21%
E. None of these
Answer: Option C
Solution(By Examveda Team)
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
$$ = \left( {\frac{{14}}{{70}} \times 100} \right)\% = 20\% $$
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A. $$\frac{1}{4}$$
B. $$\frac{1}{3}$$
C. $$\frac{1}{2}$$
D. $$\frac{2}{3}$$
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