Fast math trick for adding a series of numbers

[zeroqp]

I really love your voice. It is a big part of the reason I went back to watch more of these.

[anarcho.pacifist]

General formula: (x + y) * ((y - x) / z + 1) / 2
(where x is the start number, y is the end number and z is the step number)

Example: x = 1
               y = 7
               z = 2

(x + y) * ((y - x) / z + 1) / 2 = 16 because 1+3+5+7 = 16

[rickhanson]

Well, those were definitely some clever shortcuts. Thanks!

[kshitijabhandary]

what do you do for series that aren't continuous? how to calculate those?

[ruby-beoq]

thankyou im in year 7 and i suck at maths and you help!🍉

[boyblue]

🤯 I’ve been trying to figure this out for way too long I knew it was simple but i just couldn’t figure this out on my own. Thanks!

[shivamthaman]

what about noncontinuous no.s 20+23+25+26+27+30 its giving 150 while actual ans is 151. i guess there might be some difference b/w digits issue.

[BLR_travel]

this is only for continuous series right?

[sugarsaint]

if i had u for my teacher at school i;d have been ALLRITE !!

[kobadaa.]

Now I need to figure out how to do this in code

[jasonmurtagh]

Those mentioning n(n+1)/2 I think you'll find this will only work if you're sequence starts from 1. If you're adding a sequence of say 15-30 that formula/rule is incorrect..;)

[rhyneshiane]

How to answer if the numbers is not continuesly?

[ruiyingwu]

how do you calculate triangular numbers? please help...

[Videoorchard]

There is an more easier way to this...use N(N+1)/2 forumla..where n=number of digits! 

[AKPhantom_]

It would've been easier if you added 1+9 gives u 10 2+8 gives you 10 7+3 gives you 10 and 6+4 gives you 10 . 10 times 4 is 40 plus the 15 left over gives 55

[andrewclark]

Is there a trick for an odd number of numbers?

[minespace]

its called complements method in math.

[devyandeb]

I guess this trick will only work if the frequency are the same between each numbers

[elsonngai]

I know how to add up a group of all continous odd numbers AND a group of all continous even numbers AND continous numbers like:

(For example)
= 22878
= 99904.

And so on.

[farazkhawaja]

Careful when there’s an odd number of numbers