How to manually convert a number from decimal into binary?

Decimal and binary are two positional systems which essentially means that we write the number as a sum of digits multiplied by powers of a base. For instance, 142 actually means 10^2 * 1 + 10^1 * 4 + 10^0 * 2. The same is the case with binary, the only difference being the base is 2, not 10.

The quickest way to convert a number from decimal to binary by hand is to write down some powers of two, so 1, 2, 4, 8, 16... Then we look at our number and check which biggest power of two we could substract from it and write down a one, so if we were converting 19 base 10 into binary, we'd subtract 16 and write down just '1'. Then, for each smaller power of two (8, 4, 2, 1) if it is bigger than what is left of the number we are converting we subtract and write down another '1', otherwise we write down 0.