Hi John, thank you for reaching out. Unfortunately, this is not something related to Clay's software, but it has to do with similarweb's software, so I cannot guarantee this is true, but here is what I found on the internet:
Similarweb displays monthly visitor numbers with decimal places because their data is based on estimations generated by algorithms, meaning the numbers are not exact counts but rather calculated approximations that can include fractional values, which is why you see decimal points in the displayed data; this is especially true for high-traffic websites where precise visitor counts are difficult to obtain.
Let me know if this helps.