Alright, let's solve this problem step by step. We have 2113 and 6421 and we're adding them together.

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 & 2 in column 2 and get 3.

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

Step 4: We'll start by adding the digits 2 & 6 in column 4 and get 8.

So, 2113 + 6421 = 8534.

