According to the selected conditions, there are 200 story books in the corner of Class One, Grade Six, _ _ _ _, and how many science and technology books are there? (1) Story books are 20% less than science books _ ( 1)200÷( 1-20%),

=200÷0.8,

=250 (Ben);

How many science and technology books are there?

(2)200×( 1-20%),

=200×0.8,

= 160 (Ben);

A: Science and technology books 160.

(3)200×( 1+20%),

=200× 1.2,

=240 (Ben),

A: There are 240 science and technology books.

(4)200÷20%,

=200×5,

= 1000 (Ben);

A: Science and technology books 1000 volumes.

So the answer is: 200÷( 1-20%), 200×( 1-20%), 200 ÷ 20%.