We are presented with 4145 and 3813. Let's work out the sum.

Step 1: We'll start by adding the digits 5 & 3 in column 1 and get 8.

Step 2: We'll start by adding the digits 4 & 1 in column 2 and get 5.

Step 3: We'll start by adding the digits 1 & 8 in column 3 and get 9.

Step 4: We'll start by adding the digits 4 & 3 in column 4 and get 7.

So, 4145 + 3813 = 7958.

