Calculating infinite series is one of the more difficult parts of mathematics.

The difficulty level of this game is high.

His calculating nature sometimes causes problems.

I watched that movie three times.

The difficulty level of this problem is high.

It's difficult to solve a part of this problem.

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

I love mathematics.

This plan includes unlimited data.

In philosophy, the concept of infinity provokes very profound discussions.