Earlier 'One' was denied a seat among numbers !There is a general name given to 1 ( One), 'creator of numbers'. It was the first number created ('one', ' other than one' - 'ekam', 'anekam'). By adding one to it 'two' was born. Similarly adding another one gave three and so on. Hence the title 'creator of numbers' fell on 'one'.
Now there is the binary system using 0 and 1. This is used to create other numbers in digital technology. This is based on power 'off' and 'on' conditions.
Though the number 'one' has this much of importance, there was a time when 1 was not considered as a number at all. Plato in his famous book "Republic" asked " to what class do unity and number belong?" This raises a doubt regarding the position of 1. Al khwa reshmi ( around 825 AD), Savasorda (1100), Hispalensis (1140), Rolents (1424) and others did not consider 1 as a number. The printers Pazioli (1494), Cobel (1514) and Swivell (1505) also did not consider 1 as a number.
In 1568 English writer Baker wrote, " an unity is not a number but the beginning and origin of number".
It was from 16th century onwards 'one' started getting acceptance as a number by mathematicians.