1010 = 1 × 23  + 0 × 22 + 1 × 21 + 0 × 20
     = 8 + 0 + 2 + 0
     = 10

1010 = 10₁₀

It is convenient to remember the above fact. If you know it, then it takes just a moment to recognize 1001 = 9₁₀, 1011 = 11₁₀, and others. To convert larger binary representations to decimal representation, use a table. You can create this table from scratch.

Power of 2	10	9	8	7	6	5	4	3	2	1	0
Decimal	1024	512	256	128	64	32	16	8	4	2	1
Include?				1	0	1	0	1	0	1	0

Now think of the bits of the binary representation as turning on or off the numbers to include in the sum. For example, with 1010 1010 the various powers are turned on, as above.