If you understand binary, then this funny IT t-shirt slogan needs no explanation.
If you don't, here's a quick run-down...
In normal everyday decimal, if you start counting from 0, you get to the number 9 before needing an extra digit.
In binary, you only have zeroes and ones to count with, so if you start counting at zero, you only get as far as 1 and you run out of single-digit numbers.
To represent the number 2, you need an extra digit. The number "2", when represented in binary, is written as "10".
The number 3 is "11"
The number 4 is "100"
8 is "1000"
16 is "10000"
As such, when we say "there are 10 types of people in the world"... the joke is that 10 is actually the binary representation of the number 2, and we're actually saying that there are TWO types of people in the world.
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