{\displaystyle {\begin{array}{ll}1&\times 8+1=9\\12&\times 8+2=98\\123&\times 8+3=987\\1234&\times 8+4=9876\\12345&\times 8+5=98765\\123456&\times 8+6=987654\\1234567&\times 8+7=9876543\\12345678&\times 8+8=98765432\\123456789&\times 8+9=987654321\end{array}}}