Welcome to my most jam-packed number newsletter yet. The last of the single digits, 009 won't disappoint!

## 9th pitch drop

Scientists are fascinated by the movement of liquids. Water pouring from a tank, chemicals sluicing down a drain - for something we see every day, the mathematics of fluid dynamics are incredibly complicated. At the University of Queensland, a small jar of pitch tar has been slowly dripping … since 1930! Pitch is liquid but flows incredibly slowly - it is estimated to be 230,000,000,000 times more viscous than water!

## How slowly does pitch flow?

On 12 April 2014, after 84 years of “dripping”, just the 9th drop fell from the beaker! Holding the Guinness World Record for “longest continuously running laboratory experiment”, there is thought to be enough pitch in the beaker for it to drip for another 100 years.

## How many solvable sudoku grids are there?

You’ve probably tried a sudoku, the logic puzzle that asks you to arrange the digits 1 to 9 in grids so that no row, column or 3x3 grid contains a repeated digit. In fact, you might have tried a few. But I doubt you’ve done them all. In fact, I know you haven’t. That is because there are 6,670,903,752,021,072,936,960 unique solvable sudoku grids! (In case you’re wondering, that’s 6 sextillion, 670 quintillion, 903 quadrillion, 752 trillion, 21 billion, 72 million, 936 thousand, 960 sudokus!)

## Enjoy these fascinating numerical facts about 10!

Divisibility by 9 If the sum of the digits of a number is exactly divisible by 9, so is the original number. So for 8874; see that 8 + 8 + 7 + 4 = 27 = 3 x 9, hence 8874 is divisible by 9 (in fact it is 9 x 986). Whereas for 43765, 4 + 3 + 7 + 6 + 5 = 25, hence 43765 is not a multiple of 9.

Oh you green nine! Next time you’re blown away by something, instead of saying “well blow me down” or “I’ll be damned”, try the German “Ach, du grüne Neune!” “Oh you green nine” refers to the nine of spades in the popular card game Skat, with grüne Neune considered most unlucky.

Do cats have 9 lives? In Australia, we often speak of cats as being lucky and “having 9 lives” - for three she plays, for three she strays, and for the last three she stays". In certain regions of Spain and Germany cats are said to have 7 lives. Even less lucky are Turkish and Arabic cats – they get only 6.

## INSPIRATIONAL THINKERS & DOERS - Podcast: Billion Dollar Napkin

Okay, so because there are 9 zeros in a billion - I'm going to give a shameless plug for my latest podcast with AWS. In this six-part series, I meet some of Australia's bravest startup founders as they retrace their journey to discuss the idea that they've ultimately grown into a high-velocity business - plotting everything out on a napkin! The first two eps have dropped. Hear how the founders of crypto trading platform Swyftx went from earning $80 for a year's work to siding a $1.5 billion deal. And meet Alluvium who are creating an open-world sci-fi adventure game you can be paid to play.

## Another one for the real maths nerds (and books to be won)

The 9-digit number 438,579,088 has the incredible property that raising each digit to its own power gives the number itself. Huh? Well what this means is that 44 + 33 + 88 + 55 + 77 + 99+ 00 + 88 + 88 = 438,579,088 Apart from the trivial case that 11 = 1, there is only one other number that satisfies this property. What if I told you it was in the 3,400s - would you be able (or bothered) to work it out? And what if I told you that the first two people to email me at number@adamspencer.com.au with the correct answer will win a maths book for their troubles?! Fire away...

## Don't worry, the boys will be back

You may have heard that my beloved Sydney Swans made the AFL Grand Final … and lost badly. A lot of people have asked “have you recovered?”, “what happened?” and the like. I point out that while it was the case that a group of ugly old men beat up on a group of very talented kids, the vast bulk of the knocks I’ve heard have been from fans of the 16 teams who didn't even get the chance to see firsthand how good Geelong were that day. I hosted the Swans grand final dinner that night, which, understandably started out as a pretty sombre affair. The club was good enough to record and circulate my rallying words to the assembled faithful and, most importantly, to the team. If you love the Red and the White and need a pick-me-up, watch my rousing speech here. Yours in numbers, Adam

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