17+ 18+ 19+...+33

=( 17+33)/2X(33- 17+ 1)

=25X 17

=425

Extended data

1 Jia 100 short story: Gaussian summation

Gauss, a famous German mathematician, was brilliant in his childhood. When he was at school, one day the teacher asked the students to calculate: 1+2+3+4+? +99+ 100.

After the teacher finished the problem, the whole class was immersed in calculation, but Gao Xiao Jones quickly figured out that the answer was equal to 5050. It turns out that little Gauss found through careful observation that:

1+ 100=2+99=3+98=? =49+52=50+5 1

1 ~ 100 can be divisible by 50 logarithms, and the sum of each logarithms is equal. So, little Gauss cleverly calculated this problem as:

( 1+ 100)× 100÷2=5050。