What is the fastest way to get the 4 least significant bits in a byte (C++)?

Question

I\'m talking about this:

If we have the letter \'A\' which is 77 in decimal and 4D in Hex. I am looking for the fastest way to get D.

I thought about two ways:

Answer 1

Single AND operation can do it.

x = (x & 0x0F);