We are presented with 28 and 3505. Let's work out the sum.

Step 1: We'll start by adding the digits 8 & 5 in column 1 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 2 & 0 in column 2 and get 3.

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

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

So, 28 + 3505 = 3533.

