It's difficult to calculate the sum of this convergent series.

Solving problems of arithmetic sequence is difficult.

Understanding geometric sequences is important for understanding mathematics.

The Fibonacci sequence appears in many phenomena in nature.

He is good at solving problems related to geometric sequences.

Do you know whether he is coming or not?

What's up, you look pale.

Adding green peas to the salad makes it colorful.

Endo is my best friend.

What do you think of his ways to rule?