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Counting

4 important questions on Counting

What do the mathematical objects (disguised as words) 'and' and 'or' mean?

'And' means: Multiply
'Or' means: Add

What is the Fundamental Counting Principle, conceptually?

The conceptual definition is that the Fundamental Counting Principle is a "general way to approach tasks that can be broken into stages."

From here we can say that if we broke down a task into stages, the total number of ways to do the entire task is simply the number of ways each stage can be done, multiplied by eachother.

What is the factorial notation?

It is a mathematical pattern with a product of some integer n with all the positive integers smaller than n (example: 5*4*3*2*1)

In the context of nCr, what does 7C1 and nC1 = n, mean?

From a group of 7, we choose 1.

The number of ways I could choose 1, from a group of 7, at random is 7.
So 7C1 = 7.
Essentially, the general rule is that when you pick 1 person from a group of n people, then the number of possible ways you could pick one person is equal to n.
Hence, 7C1 = 7.

The question on the page originate from the summary of the following study material:

Magoosh Math

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