My boyfriend gave me a gift.

Everyone was surprised by the news.

He claims to be a warrior for freedom of expression, but in reality, he's just someone who uses derogatory words.

He used his alphanumeric skills to create a computer program.

Suro is my best friend.

Saburo is my best friend.

Kazumasa is my best friend.

A composite number, unlike a prime number, is represented by the product of two or more natural numbers.

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

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