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100 or "one hundred"

Roman numeral: C
In medieval times, there was a "short hundred" (100) and a "long hundred" (120)
100 is a natural number (used for counting and ordering)

Brief history of numbers

Primitive numbering started with tally marks
The first major innovation in abstraction was the use of numerals to represent numbers
Roman numerals evolved from tally marks
Another major innovation was the numeral 0 (zero)
The base-60 Babylonian numeral system was the first known positional notation system
The numeral system we all use today is the Hindu-Arabic numeral system invented between the 1st and 4th centuries by Indian mathematicians

100 math facts

100 is the square of 10 (\( 100 = 10^2 \))
100 is the sum of the first nine prime numbers \[ 100 = 2+3+5+7+11+13+17+19+23 \]
100 is the sum of the cubes of the first four integers \[ 100 = 1^3+2^3+3^3+4^3 \] ...and the square of the sum of the first four integers \[ 100 = (1+2+3+4)^2 \] ...making it a "squared triangular number"
\( 100 = 2^6+6^2 \), making it a "Leyland number"

Other fun facts

100 is the atomic number of Fermium (Fm), which was first discovered in the fallout of the first successful hydrogen bomb test
The Kármán line (100 km above the Earth's sea level) is commonly used to define the boundary between Earth's atmosphere and outer space
The US senate has 100 senators
In Greece, India, Israel and Nepal, 100 is the police telephone number
In the UK, 100 is the operator telephone number
An HTTP status code of 100 indicates that the client should continue with its request

100 degrees!

On the Celsius scale, 100 degrees is the boiling temperature of pure water at sea level (with zero being the freezing point)

Some people think 100 degrees in the Fahrenheit scale makes more sense because the 0-100 scale better represents the extremes of a habitable temperature range for humans

Numeral systems

We use a base-10 system
Computers use a base-2 system (binary)

Why do we use base-10?

Probably because we have 10 fingers. Duh.

Why do we have 10 fingers?

The Limb Law: a formula for determining the optimal number of limbs of a certain length
All mammals have five digits (or the remnants of five digits)
Extra fingers wouldn't really help much
We've got a good grip on things
It works

Numerology

The number 100 represents energy that's self-determined, independent, and has infinite potential
The number 1 represents independence, leadership qualities, and the ability to work alone
The number 0 represents openness, wholeness, comprehensiveness, and infinity
The two energies, 0 representing all that is and 1 representing aloneness, may appear to be incompatible, but they enhance each other when combined
With the influence of both the number 1 and the number 0, 100 can be seen as a virtually unlimited number 1

Centenarians

A centenarian is a person who lives to be at least 100 years old
In 2012, the UN estimated that there were 316,600 living centenarians worldwide
According to the UK ONS, a third of babies born in 2013 in the UK are expected to live to 100
About 1 in 1,000 centenarians make it to 110 years old, making them "supercentenarians"
Japan has the highest number and highest proportion of centenarians, but the female:male ratio is around 7:1

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