We've got two numbers: 5643 and 155. Let's find their sum.

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

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 7.

Step 4: We'll start by adding the digits 5 & 0 in column 4 and get 5.

So, 5643 + 155 = 5798.

