We are presented with 1086 and 603. Let's work out the sum.

Step 1: We'll start by adding the digits 6 & 3 in column 1 and get 9.

Step 2: We'll start by adding the digits 8 & 0 in column 2 and get 8.

Step 3: We'll start by adding the digits 0 & 6 in column 3 and get 6.

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

So, 1086 + 603 = 1689.

