Grades 6, 7 and 8 - Math - Middle School - Calculations - Factorials — Flashcards

A factorial is the sum of all whole numbers multiplied in ascending order that precede the factorial number until the factorial number is reached. Basically, the factorial is the sum of all the whole numbers multiplied in ascending order that precede the factorial number.

In case of the nmber 6, you find all of the whole numbers that precede (come before) the factorial number 6.  These include the numbers, 1, 2, 3, 4 and 5.  Next we are told that we include the numbers until the factorial number is reached.  This means we have 1, 2, 3, 4, 5 and 6.

Next we are told that the factorial is the sum of the whole numbers multiplied in ascending order.  This means we need to multiply each number as we ascend to the factorial number so it will look like the following:

1 x 2 x 3 x 4 x 5 x 6

So we then work to find the sum.

1 x 2 = 2
x 3 = 6
x 4 = 24
x 5 = 120
x 6 = 720  (We stop here as we have reached the factorial number.)

720 is the sum of factorial 6.

This math problem would then be written out in the following manner.

6! = 720

It can also be written as the factorial of 6! is 720.