When a honeybee constructs its combs to store its honey, it does so in such a way as to store the maximum amount of honey using the minimum amount of wax.
Without any doubt $\pi$ is the most famous of all real numbers, it appears throughout all branches of mathematics.
The exponential function $x \mapsto e^x$ and its inverse, the (natural) logarithm function $x \mapsto ln(x) (x > 0)$, are amongst the most important in mathematics, arising as they do in many different applications.
A triangle is one of the simplest configurations we can draw in the plane.
The problem of distinguishing prime numbers from composite numbers and of resolving the latter into their prime factors is known to be one of the most important and useful in arithmetic.
The last question on the Westpac Mathematics Competition, Senior Division, 1989 reads:
Before asking whether mathematics is useful, we need to know what "mathematics" means.
On January 13th of this year TIME magazine reported that Grace Hooper had died in Arlington, Virginia at the age of 85 years.
Q.872 A flea on the number line jumps from the point $a$ to the point $b$ given by $a + \frac{1}{b} = 1$.
Q.861 each of the numbers in a list $$x_1, x_2, x_3, \cdots , x_n, \cdots $$ is a positive integer written as usual in decimal notation.