Hi Rubna, For Decimal to Octal: ---------------------------- Hope you know that ,for Octal the base value is "8" and allowed digits are 0,1,2,3,4,5,6,7. For example let us take decimal value 138 Divide this number by the Octal base value and quotient becomes not divisible by base value. so 138/8 ie the remainder is 2 and Quotient is 17. Then divide the quotient by 8 ie(17/8) the remainder is 1 and quotient is 2 and this can not be divided again and so write the answers only including last quotient to the first remainder. For example in this case 0212 is the Octal value for Decimal 138.

For Octal to Decimal: ---------------------------- Powers of 8 will come into picture. For example in this the Octal Number is 0212. 2 X 8^0 +1 X 8^1 + 2 X 8 ^ 2 ,the MSB ,here is the Octal indication digit. and it will not have any impact on the conversion. The result is 2 + 8 + 128 = 138. Hope this can help you and for better understanding you have to work out by yourself. For Hexam decimal use Base 16 and digits are 0 to 9,a,b,c,d,e,f(ie 0 to 15). For Hexa decimal representation prefix is 0X(Zero X). The conversion process is the same and so you can try on that. Hope it helps you. Thanks Nirmal