We are presented with 31 and 1253. Let's work out the sum.

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

Step 2: We'll start by adding the digits 3 & 5 in column 2 and get 8.

Step 3: We'll start by adding the digits 0 & 2 in column 3 and get 2.

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

So, 31 + 1253 = 1284.

