is 2 instead of 10.we have only two sysmbols or digits (0 and 1) that can be used to in this
number system.note that the largest digit is 1 and less than the base.again each position in a
binary number represents a power of base 2. as such in this number system the right most
position is the units 2 and its exponent is 0. and the second position is counted as the unit is
2 and its exponent is 1. and than so on exponent value every time increases by 1.
thus the decimal equivalent of the binary number 10101 is
(1*2)4 +(1*2)3 +(1*2)2
+(1*2)1 +(1*2)0here 4 3 2 1 is exponent of the bracket.
so the ans is 16+0+4+0+1=21.
in order to be specific about which system are we reffering to.is is common preactice to
indicate the base as a subscript.thus we can write this similar as (10101)B=(21)D
binary digit is often reffered by the common abbreviation bit.
thus a bit in computer terminary means either 0 or 1. a binary number consisting of n bits is
called a n-bit number remember that we have only two digits 0 and 1. and hence the binary
equivalant of the decimal number 2 has to be stated as 10. and can be represented in the binary
form as an n-bit number.
