We've got two numbers: 3115 and 1381. Let's find their sum.

Step 1: We'll start by adding the digits 5 & 1 in column 1 and get 6.

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 1 & 3 in column 3 and get 4.

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

So, 3115 + 1381 = 4496.

