Key 21 on EXP39?

[CarpeDiemTim]

I apologize for asking a question that probably has an obvious answer, but where is key 21 on the EXP39? I only see 20 keys, and I'm not sure how to switch the page.

What am I missing?

Any helpful input would be greatly appreciated.

------------------------------------------------
SOLVED: Actually, I answered my own question already after coming across a manual on the website (you'd think they'd put one in the box). It explained that key1 is the one that you set to 'Switch', and it makes sense that when it's on the next page, it would become key21. Mystery solved.