My younger sister is seventeen years old.

We usually represent numbers using the decimal system.

Jumiko is my best friend.

My friend won the go tournament called Judan.

It is said that his fortune reaches a trillion billion yen.

There are twelve students in my class.

My younger sister is nineteen years old.

My younger sister is eighteen years old.

The capacity of this bottle is one koku.

His success is the result of his personal efforts.