Binary code uses how many numbers?

Easy peasy.

Binary and Hexadecimal go hand in hand. As most computers use combinations of eight bits, four bits make a total of 16. Which is the same as a hexadecimal number 0-F. So to represent the binary 1101 0011, the first 4 digits is 13 or 0xD and the last 4 is 3 or 0x3 . That makes the number 0xD3 in hex. The upper 4 bits of a byte is called the Most Significant Bits and the lower the Least Significant Bits

yes and no. the tricks come when you can come binee them