Suro is my best friend.

Kazumasa is my best friend.

The doctor measured my pulse rate.

My heart rate increases after exercise.

In the world of mathematics, an abundant number refers to a number where the sum of its divisors is greater than the original number.

In mathematics, a perfect number refers to a number where the sum of its divisors, excluding the number itself, equals the number.

In math class, I learned about deficient numbers.

Amicable numbers refer to a pair of natural numbers that have a special relationship in number theory, a branch of mathematics.

What is the play count of this video?

In Japan, 4 and 9 are considered unlucky numbers.