Without delay, let's solve this. We've got 399 and we will be multiplying it by 7, that is, adding 399 to itself 7 times.
Step 1: 0 + 399 = 399
Step 2: 399 + 399 = 798
Step 3: 798 + 399 = 1197
Step 4: 1197 + 399 = 1596
Step 5: 1596 + 399 = 1995
Step 6: 1995 + 399 = 2394
Step 7: 2394 + 399 = 2793

So, 399*7 = 2793