Not to worry, we've got 6415 and 751. Let's get to adding them!

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 & 5 in column 2 and get 6.

Step 3: We'll start by adding the digits 4 & 7 in column 3 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 6 & 0 in column 4 and get 7.

So, 6415 + 751 = 7166.

