A factorial is a function in mathematics that multiplies a number by every number that precedes it.

int main(){
    int x = 7;
    printf("The factorial of the number is %d", fac(x));
    return 0;
}

int fac(int y)
{
    if (y == 0)
        return 1;
    return y * fac(y - 1);
}

Uxntal

@on-reset ( -> )
	#0007 fac
	#010e DEO
	BRK

@fac ( n* -: res* )
	ORAk ?{ POP2 #0001 JMP2r }
	DUP2 #0001 SUB2 fac MUL2
	JMP2r