OK, let's do this. We've got 5311 and 3102 and we're adding them all together.

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

Step 2: We'll start by adding the digits 1 & 0 in column 2 and get 1.

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

Step 4: We'll start by adding the digits 5 & 3 in column 4 and get 8.

So, 5311 + 3102 = 8413.

