Here we go! We're going to add 620 and 3011 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 2 & 1 in column 2 and get 3.

Step 3: We'll start by adding the digits 6 & 0 in column 3 and get 6.

Step 4: We'll start by adding the digits 0 & 3 in column 4 and get 3.

So, 620 + 3011 = 3631.

