## If the Sum of the Digits of a Number is Divisible by Three, the Number Is Divisible by Three

Take a two-digit base-10 number where the digits are represented by ab. This number is equal to 10a + b and the sum of its digits are a + b. The difference between the number and the sum is 9a, which is divisible by three. So a + b is divisible by three, if and only… Read More »

## Harold Edgerton: “The Trick to Education Is …”

“The trick to education is to teach people in such a way that they don’t realize they’re learning until it’s too late.” — Harold Eugene “Doc” Edgerton (April 6, 1903–January 4, 1990), a.k.a. “Papa Flash”, photographer

## Can You Find Three Digits for A, B and C Such That ABC in Base-10 Is Equal to CBA in Base-9?

The only 3-digit answer is $$544_9 = 445_{10}$$. However, there are answers in other bases: $$211_3 = 112_4$$ $$322_5 = 223_6$$ $$433_7 = 334_8$$ $$544_9 = 445_{10}$$ Are you seeing a pattern here? Does the pattern extended to bases higher than 10? Does $$655_{10} = 556_{11}$$? Does $$766_{11} = 667_{12}$$? Cheating a little bit by… Read More »

## Trivia for August 2019

A tree planted in memory of George Harrison, the lead guitarist of The Beatles, died after being infested by beetles. If the sum of the digits of a number is divisible by three, the number is divisible by three. Likewise, if the sum of the digits of a number is divisible by nine, the number… Read More »

## Trivia for July 2019

Sphenopalatine ganglioneuralgia is the medical term for brain freeze (ice cream headaches). Oraibi, Arizona has been continuously inhabited since sometime around 1100 CE. St. Augustine, Florida, which makes the claim it is the oldest continuously inhabited settlement in the United States, was not founded until 1565, more than 450 years later. Damascus, Syria has been… Read More »

## What comes next in the sequence 2, 3, 7, 23, …?

Somebody asked this question on Quora. I thought I’d give it a try. The next number is 37. This is a list of prime numbers whose English names have a prime number of letters. Note: This counts letters only, not hyphens or spaces. Number Spelling Letters 2 two 3 3 three 5 7 seven 5… Read More »

## Q&A: Does Bailey’s Irish Cream Need to Be Refrigerated?

Does Bailey’s Irish Cream need to be refrigerated? No. According to Baileys—note that there is no apostrophe in their name—their Irish cream liqueur does not need to be refrigerated. In fact, they guarantee their liqueur’s taste “for two years from the day it was made, opened or unopened, stored in the fridge or not when… Read More »

## Useful Software

This post is in progress. More information is being added. Audio Editors   Audacity Website: https://www.audacityteam.org/ Platforms: Windows Free. Open Source. MediaHuman Audio Converter Website: Platforms: mp3DirectCut Website: http://mpesch3.de1.cc/mp3dc.html Platforms:   Mp3tag Website: https://www.mp3tag.de/en/index.html Platforms: OS X, Windows   Browsers   Chrome Website: Platforms: Privacy Badger for Chrome Firefox Website: Platforms: Privacy Badger for Firefox… Read More »

Everten, a company in Australia, has a Bowler Hat Colander for sale for AU$18.95 (US$ 14.42). It would make a perfect gift for your Pastafarian friend who is looking for religious headwear. Unfortunately, it looks like they only ship within Australia.