This can require many steps. At each step we simply divide the number by 2, until this finally results in a value of 0.
The remainder produced in each step (including any final remainder), give the digits of the binary conversion from l.s.b. to m.s.b.
e.g. converting 287 to binary;
Therefore 287 decimal, = 100011111 binary.
Example converting 65 to binary;
Therefore 65 decimal = 1000001 binary.
To convert a binary number to decimal, then for each bit in the number that is 1, we simply add the digit weightings together.
e.g. 1100 1011.
Therefore 1100 1011 binary, = 203 decimal.