1. Divide by 2: Continuously divide the decimal number by 2 until the quotient is 0.
2. Record the remainder: Record the remainder (either 0 or 1) after each division.
3. Reverse the order of the remainders: Arrange all the remainders in reverse order of the divisions; this will give you the binary representation of the decimal number.

Example

Converting decimal 13 to binary:

1. 13 ÷ 2 = 6, remainder 1
2. 6 ÷ 2 = 3, remainder 0
3. 3 ÷ 2 = 1, remainder 1
4. 1 ÷ 2 = 0, remainder 1

Reversing the remainders gives: 1101, so the binary representation of decimal 13 is 1101.

You can use this method to convert any decimal number!