Multiply Two Numbers
Take 3 x 6 for example.
If we start with zero and add 6 THREE times we'll get the answer.
And that is indeed how it's done!

 INP N1
 INP N2
 LDA #0
 STA ANS
LOOP: LDA N1
 BEQ END
 DEC N1
 LDA ANS
 ADD N2
 STA ANS
 JMP LOOP
END: OUT ANS
 HLT

INP N1
INP N2
LDA #0
STA ANS
LOOP: LDA N1
BEQ END
DEC N1
LDA ANS
ADD N2
STA ANS
JMP LOOP
END: OUT ANS
HLT

Assembler