How to work with numbers like 5.8E-7 in PHP?

Question

PHP

For example, how to subtract the number 5.5E-7 from the number 5.8E-7? This option is clearly not correct.$width = 5.8E-7 - 5.5E-7

Answer 1

This option is clearly not correct.

Why? https://3v4l.org/Kgdia
If you want to avoid floating point problems, you can use BC Math:
php.net/manual/en/book.bc.php