Let's solve this addition problem. We have 377 and 4001, and we need to add them together.

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

Step 2: We'll start by adding the digits 7 & 0 in column 2 and get 7.

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

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

So, 377 + 4001 = 4378.

