(Five cubed) Rectus

...has got nothing to do with the wrong end of the alimentary canal (or, digestive tract). In actual fact, it's referring to the right point... (no, I'm no longer talking about odds and ends here... wait, there may be odds later, but no ends, especially wrong ends)

Rectus is Latin for right, not as in "Correct! Correct! Correct!" (but I must confess, Linggam is ANAL) , but the rect in rectangle, which actually means right angle (90 degree angle). Now, I hope I have got off on the rectal foot, as wrong as that sounds, because this is a post about Maths...

Did you know....

• ... that I once walked up to an information counter, and asked the person there whether she knows where she kept the square root of negative one. Of course, she didn't... and I didn't go on to inquire how it's possible that a shopping complex have no complexes.


• ...that Wiener sausages are the only sausages in the world that cannot be eaten. Someone later claimed to have grown an Abelian Grape, but it was dismissed as a joke.


• ... that March 14th (3.14), is celebrated as World Pi Day... and to commemorate it, some people bake pies with the numbers in pi as the icing... also, MIT sends its acceptance letters on this important day.


• ...9 appears six consecutive times in the exact value of pi, at a point known as the Feynman Point... i.e. 3.14159...999999..., leading some of the uninformed to believe that pi could be rational due to recurring decimal places...


• ...that most mathematicians are sexually deprived? They have resorted to naming numbers using adjectives that are usually reserved for human beings... We now have sexy primes numbers, friendly numbers, amicable numbers, sociable numbers, deficient numbers, weird numbers and frugal numbers.


• ... that Murray Gell-Mann, the discoverer of the quark, once reported that he had been given an errata page that accompanied a list of random numbers. It's counter-intuitive, since we cannot tell that a number in random sets of numbers are wrong, or can we? See next point...


• ...that "random" number generators (in Microsoft Excel, Calculators, and the like) are not random... they use pseudo-random software, i.e. an algorithm that is so complicated that the strings of numbers it produces seem random enough for practical purposes and...


• ...that remote car keys have pseudo random generators in them, but the car key and the car lock have the same algorithms, so even though the password from the key seems random to you, the lock can anticipate the pseudo-random password the key will emit...

• ...that the "Six Degrees of Separation Theory" was possibly started, by Guglielmo Marconi, the inventor of the radio, who calculated that it required 5.83, rounded to 6, radio stations to cover the world.
• ...that a person's acheivements in Academia, can be measured using the Erdos Number, which is an extension of the "Six Degrees" theory, by counting the number of collaborations links a person has to make before reaching the matematician Paul Erdos.
• ...that the phrase "Infinity and Beyond" is nonsensical since there is no number larger than infinity. The Grand Hotel Paradox shows that a hotel with infinite number of rooms all filled with people, can still accomodate any amount of new guests, including an infinite amount of new guests.
• ...that according to the Pigeonhole Principle, there are at least two people in Singapore with the exact same number of hairs on their head.
• ...that you didn't have to write down all the ways to add to 10 to solve the Kindergarten Teacher's Addition Problem. The answer is 11 posters, with a total number of 511 ways to add to 10.

The solution: Treat 10 as 1 1 1 1 1 1 1 1 1 1, there are exactly 9 gaps between the 1s. To add to 10, treat each gap as a choice to place an "+". Hence, it could be 1+1+11111+111 (1+1+5+3) or 1111111+1+11 (7+1+2)... Since there are 9 gaps, there are 2^9 = 512 different ways, and ignoring the case where no + sign is placed, the answer is 512 - 1 =511.