#算法
校验信用卡号码用到的Luhn 算法，我试了一下中国的信用卡用的也是算法。
图片里的第二步“add the digits of the product(e.g. 1+6=7)”，也可以这么做：如果第一步得到的数大于9，说明是一个二位数，这时候需要减去9重新变成一位数。
BY codedump的电报频道
In recent times, Telegram has gained a lot of popularity because of the controversy over WhatsApp’s new privacy policy. In January 2021, Telegram was the most downloaded app worldwide and crossed 500 million monthly active users. And with so many active users on the app, people might get messages in bulk from a group or a channel that can be a little irritating. So to get rid of the same, you can mute groups, chats, and channels on Telegram just like WhatsApp. You can mute notifications for one hour, eight hours, or two days, or you can disable notifications forever.
Telegram’s stand out feature is its encryption scheme that keeps messages and media secure in transit. The scheme is known as MTProto and is based on 256-bit AES encryption, RSA encryption, and Diffie-Hellman key exchange. The result of this complicated and technical-sounding jargon? A messaging service that claims to keep your data safe.Why do we say claims? When dealing with security, you always want to leave room for scrutiny, and a few cryptography experts have criticized the system. Overall, any level of encryption is better than none, but a level of discretion should always be observed with any online connected system, even Telegram.
telegram from de