Your right elbow. You can try it yourself if you’re not convinced, but unless you have a broken arm or an incredibly flexible ulna, you won’t reach it.
A similar problem can be found in L.A. Graham’s Ingenious Mathematical Problems and Methods with a range of 1 to 9, but the principle remains the same – the numbers with the smallest difference produce the largest product. You start out with the highest two digits, 7 and 6, then attach 5 and 4, putting the smaller of the two digits with the larger number, giving you 74 and 65. The next two highest digits are 3 and 2, giving you 742 and 653. Finally, you add the 1 to the lower number. Page 80 has the details of that solution.
Noon and midnight are both 12 o’clock and the Twelve Days of Christmas is a popular Christmas carol.
There are twelve face cards in a standard 52-card deck and twelve is the largest number with one syllable.
There are twelve steps in Alcoholics Anonymous, a troy pound is 12 ounces, there were 12 tribes of Israel and a popular movie was called, “Twelve Angry Men” (12 members of the jury). There are twelve function keys on your keyboard. F1 often shows a help screen and F5 reloads pages in your browser.
Many recipes measure items by the dozen, adding one more for a baker’s dozen. There are twelve months in a year.
It’s surprising how many times the number twelve shows up in our culture.
On a game show there are three closed doors – one hides a car and the other two conceal a goat. The contestant selects a door, which remains closed, and the host, knowing where the car is hidden, reveals a goat behind one of the remaining two doors. The contestant is then given the option to switch doors or stay with the one they originally selected. What should the contestant do to have the best chance of winning the car?
The contestant should switch doors, which doubles the chance of winning the car. Initially there is a 2/3 chance of picking a goat, but once the other goat is revealed, switching to remaining door gives the contestant a better chance of winning the car. This is known as the Monty Hall Problem and can be very unintuitive.
Yes, there’s a 4th of July in every country. Of course they don’t treat it as a holiday as citizens of the United States do, but that’s not what was asked.