# How to add binary decimals/1s complement

From an answer sheet ....

$$0110.10_2 – 0011.01_2 = 0110.10_2 + 1100.10_{1s} = 0011.01_{1s}$$

My working from my understanding ...

 1  1
0110.10
1100.10 +
----------
10011.00


How did the .01 appear

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