Not to worry, we've got 1721 and 4070. Let's get to adding them!

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

Step 2: We'll start by adding the digits 2 & 7 in column 2 and get 9.

Step 3: We'll start by adding the digits 7 & 0 in column 3 and get 7.

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

So, 1721 + 4070 = 5791.

