Let's get this math done. We have 123 and 7131 and we're going to add them all together.

Step 1: We'll start by adding the digits 3 & 1 in column 1 and get 4.

Step 2: We'll start by adding the digits 2 & 3 in column 2 and get 5.

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

Step 4: We'll start by adding the digits 0 & 7 in column 4 and get 7.

So, 123 + 7131 = 7254.

