We've got two numbers: 5257 and 4621. Let's find their sum.

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

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

Step 3: We'll start by adding the digits 2 & 6 in column 3 and get 8.

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

So, 5257 + 4621 = 9878.

