I know this is elementary. Since new to this language and finding a sillier question in this forum, I found the courage to ask.
double x;
x = 12.5;
printf("%4.1f", &x);
warning #2234: Argument 2 to 'printf' does not match the format string; expected 'double' but found 'double *'.
When using scanf() you need the &x (address of x) so it knows where to place the value you input.
However when printing it already knows how to read x is so you can use prinf("%4.1lf",x); without the address of marker.