Binary numbers, what are they?

You may have heard about binary numbers and how they are used in computing. But after all, what are they?

In our day-to-day life we use the Hindu–Arabic numeral system, which uses ten digits to represent the numbers from zero to nine: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ( that's why we say it's a base 10 system ).

Also the position of the digit determines its contribution to the value of the number ( that's why we say it's a positional system ).

The binary system works exactly the same, but instead of ten digits it uses only two: 0, 1.
Lets count to ten in binary:

0 : zero
1: one
10: two
11: three
100: four
101: five
110: six
111: seven
1000: eight
1001: nine
1010: ten

Hexadecimal numbers

There are other bases in computing, one of them is the base sixteen or "hexadecimal", which uses sixteen digits to represent the numbers from zero to fifteen: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.

Wait, what?

It is simple, really:

0 : zero
1: one
2: two
3: three
4: four
5: five
6: six
7: seven
8: eight
9: nine
A: ten
B: eleven
C: twelve
D: thirteen
E: fourteen
F: fifteen
10: sixteen
11: seventeen
12: eighteen
13: nineteen
14: twenty