We are presented with 5406 and 1351. Let's work out the sum.

Step 1: We'll start by adding the digits 6 & 1 in column 1 and get 7.

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

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

Step 4: We'll start by adding the digits 5 & 1 in column 4 and get 6.

So, 5406 + 1351 = 6757.

