When Gauss was in elementary school, once after the teacher taught addition, because the teacher wanted to have a rest, he came up with a topic for students to calculate. The theme is:

1+2+3+

.....

+97+98+99+ 100

=

The teacher is thinking, now the children must start class! I was about to go out as an excuse, but I was

Gauss, stop! !

It turns out that Gauss has worked it out. Little friend, do you know how he did it?

Gauss told everyone how he calculated: put

1 plus

Until/very

100

and

100

increase

1

Add them to two lines, that is:

1+2+3+4+

.....

+96+97+98+99+ 100

100+99+98+97+96+

.....

+4+3+2+ 1

= 10 1+ 10 1+ 10 1+

.....

+ 10 1+ 10 1+ 10 1+ 10 1

* * * 10 1 has one hundred sums, but the formula is repeated twice, so add10/00.

Be divided by ...

2, the answer is equal to

& lt5050 >；