In this article, I will describe one of the easiest methods for converting decimal numbers to binary. It is especially useful when there are multiple numbers to convert.

Make a list of all the powers of 2, starting with 2^{0} up to the number you want to convert. Please note that this is an inclusive range. So if the number is a power of two, it must be included in the list. Make sure to write the list in descending order. For example, if the number is 73; 64 is the largest power of two which is not larger than 73. So the list must contain the numbers 64, 32, 16, 8, 4, 2 and 1. You could think of the elements in this list as the column headings of a table; please refer to the image below. Let us look at the steps needed to convert 73 to binary.

- Find the largest power-of-two which is not larger than 73. We already did that to determine how many powers of two we need in our list. We found this to be 64. Place a 1 below 64 on the list.
- Subtract the power-of-two from the number; 73 – 64 = 9.
- Repeat the first step, this time with 9 as the number. The largest power-of-two which is not larger than 9 is 8. Place a 1 below 8 in the list.
- Repeat step two with the new numbers; 9 – 8 =1.
- Repeat the first step, this time with 1 as the number. This time the power-of-two we want is the same as the number. Place a 1 below 1 in the list.
- Repeat the second step; 1 – 1 = 0. When we reach zero we can stop.
- Place zeros below all the other powers-of-two in our list. That is ones under which we have not placed a 1.
- The row below the powers-of-two list is the answer.

This method has the disadvantage that we need to prepare a list of powers of two first. But we can treat elements of this list as something like the column headings of a table. This allows us to convert multiple numbers using a single list.