Hu@Side-PalmBack Flatten

Etymology
The same handshape for with the same orientation and similar movement as the other number signs from  through.

Production

 * Repeatedly flatten and extend the index and middle fingers, keeping them together.
 * Repeatedly flatten and extend the index and middle fingers, keeping them together.
 * Repeatedly flatten and extend the index and middle fingers, keeping them together.

Adjective

 * 1) thirteen; 13