OK, let's do this. We've got 290 and 3408 and we're adding them all together.

Step 1: We'll start by adding the digits 0 & 8 in column 1 and get 8.

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

Step 3: We'll start by adding the digits 2 & 4 in column 3 and get 6.

Step 4: We'll start by adding the digits 0 & 3 in column 4 and get 3.

So, 290 + 3408 = 3698.

