Posts tagged as:

Math

Undulating Numbers

November 16, 2008

An undulating number is any number that has the form ababab… when in the base 10 number system. It is only considered after at least three digits, because otherwise all numbers below 100 would be undulating. The first 20 such numbers are: 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292 (sequence A046075 in OEIS)

Some higher undulating numbers are: 99999, 1717171, 6363, 7777, 80808.  Below 10,000 there are exactly 180 undulating numbers.

{ 0 comments }

The First Automatic Calculator

October 27, 2008

“Wilhelm Schickard built the first automatic calculator called the “Calculating Clock” in 1623. Some 20 years later, in 1645, French philosopher Blaise Pascal invented the calculation device later known as Pascal’s calculator, which was used for taxes in France until 1799. The German philosopher G.W.v.Leibniz also produced a calculating machine.”

[wikipedia]

{ 0 comments }

Fractions of Sevenths

“There is an interesting pattern with the fractions of sevenths (1/7th, 2/7th, 3/7th, 4/7th, 5/7th, 6/7th.). First, there are only 6 digits that are used in these fractions, and they repeat. So, for example, 1/7th is equal to .142857142857142857….(it keeps going). but here’’s the cool part – to get 2/7th, you just find the next [...]

[click to continue...]

The Newton

“The Physical unit “newton” is named after Sir Isaac Newton, because of the major contribution he made to the subject of Mechanics. It symbolises the amount of force required to accelerate a mass of one kilogram by one meter per second squared.”

[click to continue...]

3.14159265

“pi is 3.14159265 to 8 significant figures and is used to define the circumfrence of a circle.”
[source]

[click to continue...]

Cricket Chirps and Temperature

“If you can hear crickets chirping, the formula to calculate the temperature (in degrees Farenheit) is to count the number of chirps in 15 seconds and add 39.”
[source]

[click to continue...]

The Pacific Ocean

“The ocean encompasses a third of the Earth’s surface, having an area of 179.7 million square kilometers (69.4 million sq. mi and 161 million cubic mi) significantly larger than Earth’’s entire landmass, with room for another Africa to spare.”
[source]

[click to continue...]