We are presented with 131 and 7811. Let's work out the sum.

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

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

Step 3: We'll start by adding the digits 1 & 8 in column 3 and get 9.

Step 4: We'll start by adding the digits 0 & 7 in column 4 and get 7.

So, 131 + 7811 = 7942.

