We are presented with 8720 and 1141. Let's work out the sum.

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

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 7 & 1 in column 3 and get 8.

Step 4: We'll start by adding the digits 8 & 1 in column 4 and get 9.

So, 8720 + 1141 = 9861.

