Let's solve this addition problem. We have 4221 and 1445, and we need to add them together.

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

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 & 1 in column 4 and get 5.

So, 4221 + 1445 = 5666.

