Let's break this down. We're going to add 1645 and 2953 together.

Step 1: We'll start by adding the digits 5 & 3 in column 1 and get 8.

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 9 in column 3 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 1 & 2 in column 4 and get 4.

So, 1645 + 2953 = 4598.

