The convenient way for converting from dec to hex

       When a value x is a power of two, that is, x = 2 ^ n for some nonnegative integer n,

we can readily write x in hexadecimal form by remembering that the binary representation

of x is simply 1 followed by n zeros. The hexadecimal digit 0 represents four binary zeros.

So, for n written in the form i + 4j, where 0 <= i <= 3, we can write x with a leading hex digit

of 1(i = 0), 2(i = 1), 4(i = 2), or 8(i = 3), followed by j hexadecimal 0s. As an example, for

x = 2048 = 2 ^11, we have n = 11 = 3 + 4 * 2, giving hexadecimal representation 0x800.

                             ---------- From  Computer System A Programmer's Perspective Page 35