Good morning everyone! Happy 2023! Today’s post is in honor of two new years.

The first is the new calendar year: 2023. If you want to do something fun (which of course you do) then you can see if you can use exactly the digits 2, 0, 2 and 3 and different math configurations to write the numbers 1-100. For example: . Or . (There are examples all over the internet, so a quick search reveals many solutions should you wish.)

The other is the Lunar New Year, which began yesterday. This is also known as the Spring Festival, and is observed around the world, including China, Indonesia, Japan, Malaysia, the Philippines, Singapore, South Korea, Taiwan, Thailand, and Vietnam: we are now in the Year of the Water Rabbit in many countries, and the Year of the Cat in Vietnam.

In honor of the New Year we’ll talk about the mathematician Jing Fang 京房. He was born in China 2100 years ago (78 BCE, during the Han Dynasty). He was a mathematician and, appropriately enough for this post, he described astronomy – the solar and lunar eclipses.

But these weren’t his only accomplishments. He was also very good at making predictions using the *Yijing*, or *I Ching*. There are 64 hexagrams, each made up of 6 rows that have one long or two short marks in each row. While this isn’t mathematics, it does lead to the math question to ponder: namely, can you explain why there are exactly 64 configurations?

And his math-connection doesn’t end there either – he used mathematics to describe music theory, particularly that 53 fifths (technically “just fifths”, which may or may not be the same as a perfect fifth – but you can here one here) was almost exactly 31 octaves. It took more than 1600 years for anyone (said anyone being Nicholas Mercator) to caculate the difference between the two more exactly than Jing Fang.

Math Moons and Music – a good way to start the year.

Sources: Wikipedia and…just that, because the few other sources I found had the same information.