We've got two numbers: 7000 and 3661. Let's find their sum.

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

Step 2: We'll start by adding the digits 0 & 6 in column 2 and get 6.

Step 3: We'll start by adding the digits 0 & 6 in column 3 and get 6.

Step 4: We'll start by adding the digits 7 & 3 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 7000 + 3661 = 10661.

