Okay, we are given 1815 and 2050. Let's add them up step by step.

Step 1: We'll start by adding the digits 5 & 0 in column 1 and get 5.

Step 2: We'll start by adding the digits 1 & 5 in column 2 and get 6.

Step 3: We'll start by adding the digits 8 & 0 in column 3 and get 8.

Step 4: We'll start by adding the digits 1 & 2 in column 4 and get 3.

So, 1815 + 2050 = 3865.

