Math question


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What's it called when you take a series of numbers, starting from one variable and working either higher or lower till you get to zero, adding the sum of all the numbers along the way?

i.e. number is 50 so declining from 50 to 0 we add 50, 49, 48, 47, 46, etc till we get a total of all the numbers until reaching zero?

Does someone know if there's an option on calculators to figure this quickly with larger numbers?

Thanks!

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Not sure for adding but I know factorial which is like 9! = 9x8x7x6x5x4x3x2x1 usually scientific calculators have the '!' Function

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I don't think the function has a name as such... but if what I think you're talking about is correct it has a much more generalised formula:

Where n is the variable in question, the addition of all the numbers from 0 to n is: (n*(n+1))/2

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What you are talking about is called Summation:

http://en.wikipedia.org/wiki/Summation

You will find a quick formula for doing what you want at that link but its basically as follows:

Say you want to find the sum of numbers from 1 to 50 (in your example)

So you take the max number (50) and multiply it by one higher (51)

This gives the value 2550.

You then divide this by 2 giving the answer 1275 and that is the value of the sum of numbers 1 - 50.

You can test this out with a smaller range (eg the sum of numbers 1-5)

So Max number is 5 multiplied by one higher (6) = 30.

Then divide by 2 = 15.

1 + 2 + 3 + 4 + 5 = 15

QED :)

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