Without delay, let's solve this. We've got 798 and we will be multiplying it by 5, that is, adding 798 to itself 5 times.
Step 1: 0 + 798 = 798
Step 2: 798 + 798 = 1596
Step 3: 1596 + 798 = 2394
Step 4: 2394 + 798 = 3192
Step 5: 3192 + 798 = 3990

So, 798*5 = 3990