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Algebra Level 2

What is the value of :

10 + 20 + 30 + … + 190 + 200 ? 10 + 20 + 30 + \ldots + 190 + 200 ?


The answer is 2100.

Anish Harsha by Anish Harsha , 20, India

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5 solutions

A = 10 + 20 + 30 + . . . + 190 + 200 A=10+20+30+...+190+200

A = 10 × ( 1 + 2 + 3 + . . . + 19 + 20 ) A=10 \times (1+2+3+...+19+20)

A = 10 × 210 = 2100 A= 10\times 210 = \boxed{2100}

4 Helpful 0 Interesting 1 Brilliant 0 Confused

did the same way! ⌣ ¨ \ddot\smile

Rohit Udaiwal - 5 years, 10 months ago
Chelsea Long
Jul 30, 2015

If you add biggest # and smallest #, you have 210. 2nd biggest and 2nd smallest = 210, etc. Do this all the way down, and you have 10 sets of 210. 10x210=2100

3 Helpful 0 Interesting 0 Brilliant 0 Confused
Anish Harsha
Jul 16, 2015

Simple. Just imagine that the numbers are 1+ 2+ 3...+19 + 20. If we add the numbers, the answer comes 210. If we re-add 0, the answer becomes 2100 .

3 Helpful 0 Interesting 0 Brilliant 0 Confused

that's what I did

Crash Ackerly - 5 years, 10 months ago

I did not understand. Anything am like going to myself What.,!😯😯

Mars Rivera - 5 years, 10 months ago
Azadali Jivani
Jul 28, 2015

sum=20(10+200)/2=2100

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Brendon Teong
Aug 24, 2020

\(10+20+30.......+190+200=

(200+10)\times 10=2100\)

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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