We've got two numbers: 4015 and 861. Let's find their sum.

Step 1: We'll start by adding the digits 5 & 1 in column 1 and get 6.

Step 2: We'll start by adding the digits 1 & 6 in column 2 and get 7.

Step 3: We'll start by adding the digits 0 & 8 in column 3 and get 8.

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

So, 4015 + 861 = 4876.

