We are presented with 1313 and 3981. Let's work out the sum.

Step 1: We'll start by adding the digits 3 & 1 in column 1 and get 4.

Step 2: We'll start by adding the digits 1 & 8 in column 2 and get 9.

Step 3: We'll start by adding the digits 3 & 9 in column 3 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 1 & 3 in column 4 and get 5.

So, 1313 + 3981 = 5294.

