(by Peter Rowlett)

Solve this equation for x. Then rotate 180° and solve for x again.

The equation works either ways as 𝑥, 1, 8 and the unusual 5 have rotational symmetry. The same is true of +, =, and the horizontal line in a fraction.

## “Magic” Factorials

There are many fun facts regarding the factorials. For instance:

- 0! = 1 by convention. As weird as it may sound, this is a fact that we must remember.

- The number of zeroes at the end of
*n*! is roughly*n*/4. - 70! is the smallest factorial larger than a
.*googol* - The sum of the reciprocals of all factorials is
.*e* - Factorials can be extended to fractions, negative numbers and complex numbers by the
.*Gamma function*

It is possible to “peel” each layer off of a factorial and create a different factorial, as shown in the neat number pattern below. A prime pattern can be found when adding and subtracting factorials. Alternating adding and subtracting factorials, as shown in the picture, yields primes numbers until you get to 9! Continue reading ““Magic” Factorials”

## Surprising Limit

Amazingly, this sequence of fractions converges to 0.70710678118…, or to be precise, to √2/2. The sequence is related to the Prouhet-Thue-Morse sequence.

## Prime Fractions

Did you know? You can write the number 1 as a sum of 48 different fractions, where every numerator is 1 and every denominator is a product of exactly two primes.

This problem is related to the Egyptian fractions.

## Very Large Numbers In Real Life

Most people know about Zimbabwe’s trillion dollar bill notes or have heard stories about Germans using worthless Marks during the Weimar Republic for wallpaper, but what few realize is that Hungary broke all the records. Just after the WWII, between 1945 and 1946, Hungary was in a state of hyperinflation, with inflation rates reaching **41.9 quintillion percent** (that is 41,900,000,000,000,000,000%). Continue reading “Very Large Numbers In Real Life”

## Sum of Infinite Power Series

Have a look at the two distinct sums of series of powers below.

Same procedure, different result accuracy levels… Can you guess what went wrong in the operation of fig. 2?

## The Plant That Is Able To Count Almost To Five

We already knew birds can count, but what about plants? Is this idea so surrealist? No, it isn’t because research says the carnivorous plant with a suggestive name, *Venus Flytrap* (also referred to ‘Dionaea muscipula’), snaps its jaws shut only when the tiny hairs on the surface of the trapping structure formed by two lobes have been stimulated twice within a 20-second window. An additional stimulation primes the trap for digestion. Five stimulations trigger the production of digestive enzymes – and more additional hairs’ stimulations mean more enzymes.

Continue reading “The Plant That Is Able To Count Almost To Five”

## Numbers In Nature

*Diaethria phlogea*, the “89’98 butterfly”, is a species of butterfly of the Nymphalidae family found in Colombia, South America. The markings on its wing resemble a painted number: an 89, a 98 or even an 88.

Are there any other animals with numbers painted on their body?