About 7000 years ago, the Egyptians started to use a number system linked to units, tens, hundreds etc.
old things thousands of years before Christ
7000 years ago Babylonians use multiplication tables
They also use Pythagoras's Theorem 4000 years ago , and can solve quadratic equations. But they still don't even have any 0's (Zero) for another 2000 years.
Jan 1, 1225
Letters used in algebra
Letters seem to have been first used instead of numbers in algebra, to represent numbers which we don't know. Sometimes these letters represent fixed numbers (constants) and sometimes they can be chosen (variables)
Jan 1, 1248
Li Yeh writes a book which contains negative numbers, denoted by putting a diagonal stroke through the last digit. We now use the -sign e.g. -18
Jan 1, 1492
Francesco Pellos wrote a commerical arithmetic book, Compendio de lo abaco, in which he made use of a dot to denote the divison of an integer by a power of ten. This led to the development of what we now refer to as a decimal point.
Jan 1, 1557
The equals sign
Robert Recorde parallel lines (=) to represent the equals sign for the first time
First calculating machine
A mathematician called Schickard makes a wooden calculating machine that can add and subtract, and help with multiplication and division.
Hand held calculator
A Texas Instuments developed a calculator small enough to be held in your hand.
The previous calculat whighed as much an average year 8 pupil!
prime numbers used for codes
Adleman, Rivest, and Shamir introduce public-key codes, a system for passing secret messages using large prime numbers. This is the basis of security for bank cards and internet shopping.
Zero (O) is recognised and used
Zero is used. Before this there wasn't a symbol for Zero. There were already marks used to represent a space in one of the collumns (like the 0 in 2012), but there had not been a symbol for none (like zero sheep)