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Mouse-2002, 27 bytes
B! prints 1, because B's address is 1.
ZR+! prints 42, because 25 17 + 42 = is 1.
Newline separated (but if put in different (or one) file/s, no newline is needed, and if not for visuals it would look like A!B!C!D!E!F!G!H!I!J!K!ZR+!):
A!
B!
C!
D!
E!
F!
G!
H!
I!
J!
K!
ZR+!