Wiping USB flash drive. How many pes?

Hi, I read hard drives magnetic like the ones in your computer need to have about 7 pes so that data previously on the drive isn't even recoverable by forensic tools like electronic microscopes. (you who don't understand, a hard drive still holds data even if you deleted the file. so long to copy a file but deleting it takes 1 second. It's because Windows just says file off the drive's table of contents but the file is still on the drive. Special software can recover the file but so let's overwrite the drive with another file. Now the software can't recover it. That's what wiping. It takes all deleted files and wipes with random 1s and 0s. But not end of story. Special equipment that government uses look at drive and see data bit on drive isn't a 1 or a 0. It's 0.8. The government &high end recovery labs use microscope. 0.8 means the data in previous file was a 0, but now it's a 1. A 0.4 means it is sometimes a 1 mostly a 0. So the idea is garble 7 pes.) How many wipes for flash?