A fair coin tossed 10 times will have 210 = 1024 possible outcomes.
1 of those is "no heads"
10 of those are "one head". (The one head can be first. The one head can be second. ...)
Thus, 2 or more heads will show up in (1024 - 11 = 1013) of the outcomes.
The probability of 2 or more heads in 10 tosses of a fair coin is 1013/1024.
