1/200+2/200+3/200+…+199/200.
问题描述:
+1 200
+2 200
+…+3 200
. 199 200
答
+1 200
+2 200
+…+3 200
,199 200
=
,(1+199)×199÷2 200
=
,200×199÷2 200
=
.199 2