In TPT?
Or in real life?
Or in computer code?

1. Translate them to binary ( 0 = 0, 1 = 1, 2 = 10, 3 = 11, 4 = 100, 5 = 101, 6 = 110, 7 = 111, 8 = 1000 etc) via a mesh.^{[Example 0]}
2. Make a binary adder core.^{[Example 1]}
3. Make a series of AND gates that translate binary back to decimal.

Numeric systems:
You got decimal, which consists of 10 numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. After that, it goes to combine such numbers as 10, 11, 12 etc.
You got hexadecimal, which consists of 16 numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. After that, it starts combining as 10, 1A, FF etc.
You got octal, which consists of 8 numbers: 0, 1, 2, 3, 4, 5, 6, 7. After that, it combines as before.
You got binary, which can be represented with spark on and spark off in TPT.
That has two numbers: 0, 1. After that it combines like the rest. 10, 11, 100 101, 110 etc.
The hard part is converting between these parts.
As 13 represents D in decimal(decimal to hex), does 11 represent 3 in binary(binary to decimal)
 

@Vou
There's a joke about that
In the world there are 11 types of people: people who know binary, people who don't and people who have already heard this one.