We've got two numbers: 3502 and 6291. Let's find their sum.

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 & 9 in column 2 and get 9.

Step 3: We'll start by adding the digits 5 & 2 in column 3 and get 7.

Step 4: We'll start by adding the digits 3 & 6 in column 4 and get 9.

So, 3502 + 6291 = 9793.

