OK, let's work through this together. We're starting with 336 and we're going to multiply it by 5, which means we add 336 to itself 5 times.
Step 1: 0 + 336 = 336
Step 2: 336 + 336 = 672
Step 3: 672 + 336 = 1008
Step 4: 1008 + 336 = 1344
Step 5: 1344 + 336 = 1680

So, 336*5 = 1680