Let's get this math done. We have 343 and we're going to multiply it by 5. This is the same as taking 343 and adding it to itself 5 times.
Step 1: 0 + 343 = 343
Step 2: 343 + 343 = 686
Step 3: 686 + 343 = 1029
Step 4: 1029 + 343 = 1372
Step 5: 1372 + 343 = 1715

So, 343*5 = 1715