Let's solve this addition problem. We have 145 and 6620, and we need to add them together.

Step 1: We'll start by adding the digits 5 & 0 in column 1 and get 5.

Step 2: We'll start by adding the digits 4 & 2 in column 2 and get 6.

Step 3: We'll start by adding the digits 1 & 6 in column 3 and get 7.

Step 4: We'll start by adding the digits 0 & 6 in column 4 and get 6.

So, 145 + 6620 = 6765.

