Good to know

The Variables you can use are $\displaystyle A$ to $\displaystyle F$, $\displaystyle M$, $\displaystyle X$, and $\displaystyle Y$. The Mode must be NORMAL. The Ending: the expression can only end with =, not with M+ or another ending instruction. If you press ON/C by mistake, press the up arrow: the expression returns, and you can continue.

▶ Watch this step in the video (1:14:35)