Is 90.90 equivalent to 90.9

Oh, dude, like, technically speaking, 90.90 is not exactly the same as 90.9. The first one has an extra zero at the end, which makes it slightly different. But hey, if we're talking about significant figures or something, then yeah, they're basically the same. So, like, it really depends on how picky you wanna get with your numbers, you know?