Nine coins are placed in 8 rows of 3 coins each.

$\displaystyle \begin{array} {ccccc}

O &\to& O &\to& O \\

\downarrow & \searrow & | & \swarrow & \downarrow\\

O &\to& O &\to& O \\

\downarrow & \swarrow & \downarrow & \searrow & \downarrow \\

O &\to& O &\to& O \end{array}$

Move two coins and form 10 rows of 3 coins each.