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What percentage of the numbers from 1 to 50 have squares that end in the digit 1 ?
Answer & Solution
Correct Answer:
Option
E
The squares of numbers having 1 and 9 as the unit's digit end in the digit 1.
$$\eqalign{ & {\text{Such numbers are,}} \cr & 1,9,11,19,21,29,31,39,41,49{\text{ i}}{\text{.e}}{\text{.,}} \cr & {\text{There are 10 such numbers}}{\text{.}} \cr & \therefore {\text{Required percentage}} \cr & = \left( {\frac{{10}}{{50}} \times 100} \right)\% \cr & = 20\% \cr} $$
$$\eqalign{ & {\text{Such numbers are,}} \cr & 1,9,11,19,21,29,31,39,41,49{\text{ i}}{\text{.e}}{\text{.,}} \cr & {\text{There are 10 such numbers}}{\text{.}} \cr & \therefore {\text{Required percentage}} \cr & = \left( {\frac{{10}}{{50}} \times 100} \right)\% \cr & = 20\% \cr} $$
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