The decimal equivalent of fraction 2/15 is,
[tex]\frac{2}{15}=0.13333333[/tex]The number 3 is repeating in the decimal. So, we should overline 3.
Then, the decimal decimal equivalent of fraction 2/15 becomes,
[tex]0.1\bar{\text{3}}[/tex]Hence, the number of digits to be overlined is one.
The decimal equivalent of 3/10 is,
[tex]\frac{3}{10}=0.3[/tex]