Okay, we are given 4221 and 3446. Let's add them up step by step.

Step 1: We'll start by adding the digits 1 & 6 in column 1 and get 7.

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

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 4 & 3 in column 4 and get 7.

So, 4221 + 3446 = 7667.

