We've got two numbers: 1608 and 391. Let's find their sum.

Step 1: We'll start by adding the digits 8 & 1 in column 1 and get 9.

Step 2: We'll start by adding the digits 0 & 9 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 3 in column 3 and get 9.

Step 4: We'll start by adding the digits 1 & 0 in column 4 and get 1.

So, 1608 + 391 = 1999.

