The sum of all odd numbers form 1 to 99 is?

use sum of aritmetic sequence. .

1 + 3 + 5 + 7.....But you need not do that since it is an arithmetic sequence.

The sum of an arithmetic sequence is: \(\Large \color{Black}{\Rightarrow {n \over 2}(a_1 + a_l) }\) a1 is the first term aL is the last n is the number of terms

After 1 add? Should i cross multiply?

1st term is 1. Last is 99. Odd numbers between 1,100 are 50.

The common difference is d, btw.

@ParthKohli , i think you've mistaken the formula. . http://www.regentsprep.org/Regents/math/algtrig/ATP2/ArithSeq.htm

Oops, it was aN lol

it's ok. .

I dont get it XD

Hey I know another pattern.

The sum of first n odd numbers is n squared. The sum of first 50 odd numbers is 50 squared. So, 50^2 = 2500

Well actually my formula was correct.

I learnt this pattern at school.

Ca you give me an example?

For example the sum of first 4 odd numbers is 4 squared aka 16 1 + 3 + 5 + 7 = 4 + 12 = 16

how did you got that formula? @ParthKohli

Oh wait a second

Yes....yes I'm correct.

the answer is 2500, and you're correct, but how did you get that another formula?

I learnt that at school

@sel126 Got it?

Yessss :) Thankyousomuch:)))))))

Yw :D

99 = a + (n-1)d hence 99 = 1 +(n-1)*3 n= 50 substituting value of n in equation S= n/2 [ 2a + (n-1)*d] we get sum of odd terms that is equal to 2500 where a =1(first term) and d =3(common difference)

Why does three become the d?

the sum of odd numbers is a perfect square

That's what I said above

Hehe don't waste your energy, genius. I've explained her.

just thought i would mention it. no need for a formula, or all that other business, only need to know how many numbers are being added

Hmm I said the exact same thing.

Still here you have a medal

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