My book says 0010 1010 in binary notation equals to 42. Then if you use hexadecimal you can break that down into 2A. My book says 

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> 2 = (2 \* 16 = 32) A = (10 x 1 = 10) so 32 + 10 = 42
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I'm totally lost. I don't understand, if you're starting from the right to left, why the values of the first four digits are 2 + 8 = 10 = A. Why is then 32 equal 2 and not 32. Aren't you counting the totals? 

And why are you multiplying 10 by 1 and then 2 by a different value of 16?