Xiao Ming and Xiao Chen carry books, Xiao Ming carries 18 copies each time, and Xiao Chen carries 2 1 copies each time, and each of them carries 135 copies. How many times have you asked Xiaoming and Xiao Chen to recite books? Xiaoming delivers 18 copies at a time, which is a multiple of 9.

Xiao Chen delivers 2 1 serving at a time, which is a multiple of 3.

Two people recite 135 books, which is a multiple of 9. Then the number of Chen Xiaoyun should be a multiple of 3.

Xiao Ming always brings even books, while Xiao Chen must bring odd books. Xiao Chen's times must be strange, too.

Then Xiao Chen may have delivered 3, 9, 15 ... times, and more times will exceed the total.

135 ÷ 2 1 = 6.43

Obviously, Xiao Chen has been lucky three times.

Xiao Ming is lucky (135-21× 3) ÷18 = 4 times.