Are division and Hailstone primitive recursion function?$$\text{Div}(x,y) = \begin{cases}x/y,  & \text{if $y$ divides $x$ } \\0, & \text{otherwise}\end{cases}$$ $$\text{Hailstone}(n) =\begin{cases}3n + 1,  & \text{if $n$ is odd } \\n/2, & \text{if $n$ is even}\end{cases}$$ I tried to solve division in this way$$\text{Div}(0,y) = 0 $$$$\text{Div}(x+y,y) = \text{Div}(x,y) + 1$$I do not know how to proceed from here. Can anyone help me? 
Primitive Recursive Function for Division and Hailstone function
computability;primitive recursion