Not to worry, we've got 619 and 6126. Let's get to adding them!

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

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

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 7.

Step 4: We'll start by adding the digits 0 & 6 in column 4 and get 6.

So, 619 + 6126 = 6745.

