FOUR OR ZERO (Easy)

Charlie and Johnny play a game. For every integer $X$ Charlie gives, Johnny has to find the smallest positive integer $Y$, such that $X$ * $Y$ contains only 4's and 0's and starts with one or more 4's followed by zero or more 0's. (i.e.), 404 is an invalid number but 400 is a valid number. If $a$ is the number of 4's and $b$ is the number of 0's, can you print the value of 2 * $a$ + $b$. ###Ca