Using (*,*) means you don’t have to worry so much about the print string formatting. But I know what you mean about doubting everything. Sometimes I just use something like write (*,*) "XXXXXXX" just to see if a particular block of code is even executing. Or if you have a complex calculation, it’s often helpful to break it up and print out intermediate parts (numerators and denominators), as in this example: https://mfix.netl.doe.gov/forum/t/segmentation-fault-invalid-memory-reference-in-tfm-simualtion/2674/34 - if you’re just printing numbers, you don’t really have to worry about format strings.