Remember the divisibility rule for 9. The sum of the digits of the number must be divisible by nine.
Let the digit be [tex] x [/tex]. Then [tex]x+3+5+2+0=x+10[/tex] has to be divisible by nine. Recalling that [tex] 18=9*2 [/tex], we note that [tex] x=8 [/tex].
