Now let's use this template on that ugly binary number from our earlier example. At the top is our template, at the bottom is our binary number:
128 
64 
32 
16 
8 
4 
2 
1 

1 
0 
1 
0 
1 
1 
1 
0 
Now we use simple multiplication and addition. If the binary number is a 1, it means this digit is "on" or "true" and we add the corresponding number from the template, if it is a 0, it means the digit is "off" or "false", and we do not add the corresponding number from the template.
In our example, the digits for 128, 32, 8, 4 and 2 are true, so we add
128 + 32 + 8 + 4 + 2 = 174
You could also express it as
128*1 + 64*0 + 32*1 + 16*0 + 8*1 + 4*1 + 2*1 + 1*0 = 174
This means our binary number 10101110 is the number 174 in the decimal system.
Page 1: What is the binary system
Page 2: This page
Page 3: Bits vs bytes, some terminology
Page 4: Bus width
