We have numbers 2840 and 1051. Let's start adding them together.

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

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

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 2 & 1 in column 4 and get 3.

So, 2840 + 1051 = 3891.

