How to convert decimal to hexadecimal using brain?

Question

Since I knew how to manually convert hexadecimal to decimal using this method. Read from right to left, the last digit multiplied by the constant value 16 and plus the first digit.

For example:
12h = 2 + (1 * 16) = 18
99h = 9 + (9 * 16) = 153

How do I convert back into hex from decimal?

Answer 1

As you can see in the picture above. You need to draw a table in your brain

Lets take 456 as example.

If we divide 456 by 16 . Remainder = 8 & Quotient = 28

We further divide 28 by 16 and get remainder = 12 & quotient = 1

Now further dividing 1 by 16 results in remainder = 1 and quotient = 0

So we stop.

Now we take the remainders, bottom up.

1 , 12 , 8

Converting 12 in hex notation gives C.

So the answer is 1C8

Answer 2

To convert from decimal to hex you must know the powers of 16. 16^1 is obviously 16; 16^2 is 256; 16^3 is 4096; 16^4 is 65536; etc.

For each power of 16, divide the number by that power to get one hex digit. Then take the remainder and divide by the next lower power of 16.

This is enough of a hassle that it's easiest to let a calculator do it, or use a scripting language such as Python.