We are presented with 7111 and 1523. Let's work out the sum.

Step 1: We'll start by adding the digits 1 & 3 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 & 5 in column 3 and get 6.

Step 4: We'll start by adding the digits 7 & 1 in column 4 and get 8.

So, 7111 + 1523 = 8634.

