9. $1 \times 1=1, 2 \times 2=4, 3 \times 3=9, 4 \times 4=16, \ldots \ldots$, the products $1, 4, 9, 16, \ldots \ldots$ in the expressions are called perfect squares. Among the 100 natural numbers from 1 to 100, the sum of all non-perfect square numbers is $\qquad$
Reference answer: 4665