let
x-----> number one
y-----> number two
we know that
x=y²--------> equation 1
x+y=650-----> equation 2
substitute 1 in 2
[y²]+y=650-------> y²+y-650=0
using a graph tool-------> to resolve the second order equation
see the figure attached
the solution is
y=25
x=650-y-----> x=650-25------> x=625
the answer is
the numbers are 625 and 25