How do you evaluate 11C7?
The general formula for combinations is:
This notation can seem confusing at first, but it basically just means the following:
We can make the calculation easier by cancelling first:
This leaves us:
As a quick tip. Notice that what we are removing from the numerator is
What remains in the denominator is #11 - 7 = 4.
This is the
We know this at the start because we had the 11 and the 7'
These are the quick ways of evaluating by hand. A calculator is much quicker, but where's the fun in that :)
Hope this helps you.