OK, let's do this. We've got 5125 and 1805 and we're adding them all together.

Step 1: We'll start by adding the digits 5 & 5 in column 1 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 2 & 0 in column 2 and get 3.

Step 3: We'll start by adding the digits 1 & 8 in column 3 and get 9.

Step 4: We'll start by adding the digits 5 & 1 in column 4 and get 6.

So, 5125 + 1805 = 6930.

