Question 202161
I'm not clear on your question. I think you are asking
What is {{{101[2]}}} in base 10?
If that is the case, then you need to understand that the each column in the binary system has a specific value. Just like each column in base ten has a value.

In base ten, the lowest order column (digits) represents {{{10^0}}} = 1
The next higher column represents {{{10^1}}} = "the tens"
The next one up is {{{10^2}}} = "the hundreds".

Same idea in other base systems. 
For binary (base 2), 
the lowest order column (digits) represents {{{2^0}}} = 1
The next higher column represents {{{2^1}}} = "the twos"
The next one up is {{{4^2}}} = "the fours" etc

So the number you are given is {{{101[2]}}} 
Thus you have 1 in the digits. so that is 1*1 = 1
You have 0 in the twos. 2*0 = 0
You have 1 in the fours. 4*1 = 4
Total is 4+0+1 = 5
So {{{101[2]}}} = {{{5[10]}}}

The same process holds for any base you choose. Popular bases include 2, 8, 10 and 16 as far as computers are concerned. can you think of a case where base 12 occurs in real life?  
Take your "time" and think about it