LDX #18
LDY #7
STX $50
STY $51

multiply: ; multiply the number in the location $50 by the number in the location $51 and store it in the location $52. Give an incorrect answer if the result is above 255
LDX #0
LDA #0
add:
CPX $51
BCS there
ADC $50
INX
JMP add
there:
STA $52