Here we go! We're going to add 421 and 1452 together.

Step 1: We'll start by adding the digits 1 & 2 in column 1 and get 3.

Step 2: We'll start by adding the digits 2 & 5 in column 2 and get 7.

Step 3: We'll start by adding the digits 4 & 4 in column 3 and get 8.

Step 4: We'll start by adding the digits 0 & 1 in column 4 and get 1.

So, 421 + 1452 = 1873.

