Now we are learning about the binary system .The earliest computers were abacus's but when electricity kicked in after WW1 computers just got more powerfull .
Computers work like this : they use electricity . Electricity can be on or off. "On" is 1 and "off" is 0 . Well that wouldnt't be too helpfull. But it can count using these numbers , how ?Well there are place holders like 10 or 100 or 1000 and they get bigger by ten.In the binary system you use a thing callled the binary code which are powers of 2 like :1, 2 , 4, 8 , 16 , 32 , 64, 128 etc...
An example will show how this works the best way .
THe number you want to obtain in binary is 64 .notice the way the code goes from right to left.
Binary code 256 128 64 32 16 8 4 2 1
Binary number 1 0 0 0 0 0 0

If you want 12 it's 1 1 0 0
because 4+8 is 12

It's hard to make a chart here . All you have to do is to like check the numbers from the binary code with a one and add them till you get your desired regular number .If you dom't need that number it's a zero.
0 or 1 is called a bit . 8 bits are a byte and the rest folow the metric system like a killobyte , megabyte , gigabyte , terrabyte. This is the way computers make calculations .