问题 填空题
C03
+
C14
+
C25
+…+
C69
=______.(用数字作答)
答案

原式=

C33
+
C34
+
C35
+…+
C39
=
C44
+
C34
+
C35
+…+
C39
=
C49
+
C39
=
C410
=210

故答案为:210.

计算题
填空题