Perhaps the ancient men counted on fingers. If we got 6 fingers per hand, many things would be easier - since we have 12 months in year, 12 hours on clock, 12 semitones in musical scale, division of 12 can be done more ways than ten (we can divide 12 in 2,3,4,6 without rest) etc.
There is no decimal number for the binary number 13 because 13 cannot be a binary number.
The decimal system is based on the number ten.
They use the binary sysem because the number 1 means the switch is turned on and the number 0 means the switch is off. There is no way to use the decimal number system.
Because the decimal system is based on 10 ("decem" = 10 )
Decimal system
The decimal number system.
Decimal.
The decimal system.
Because it is the decimal number system. Which means there are ten digits. Other number systems end at other points. The binary number system ends at 1 for instance.
030 is 30, which is a number in the decimal system.
The decimal system is one of numbers, not of measurement. A decimal number is simply a way of representing a number in such a way that the place value of each digit is ten times that of the digit to its right.
The decimal system is the same anywhere. Dec means 10 so the decimal system is a system used on the base 10 system.