# The Birthday Of Anwesha Biswas Tithi

**Number Theory**Level 3

Find a decimal number which can be represented with 1's only and no 0's in binary, and takes 4 bits in binary. In other words, if you convert that decimal number into binary, it cannot be like 10101 which does contain 0's. It should only contain a certain number of 1's.

Submit your answer as the sum of digits of the **binary-coded decimal** of that decimal number.

For binary-coded decimal, read the wiki Binary-Coded Decimal.