We have numbers 8102 and 1351. Let's start adding them together.

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

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

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 8 & 1 in column 4 and get 9.

So, 8102 + 1351 = 9453.

