OK, let's crack this. We're given 343 and our task is to multiply it by 3. Essentially, we'll be adding 343 to itself 3 times.
Step 1: 0 + 343 = 343
Step 2: 343 + 343 = 686
Step 3: 686 + 343 = 1029

So, 343*3 = 1029