1+3+5+7+。 . . . . . +97+99
=( 1+99)+(3+97)+(95+5)。 . . +(49+5 1)
=50/2× 100
=25× 100
=2500
1+3+5+7+。 . . . . . +97+99=(25)x( 100)=(2500)
(If you don't understand, you can ask and hope to adopt)
A. How do sixth-grade graduates from Guangdong and Education apply for the first grade?
If your account and password are the