OK, let's crack this. We're given 670 and our task is to multiply it by 5. Essentially, we'll be adding 670 to itself 5 times.
Step 1: 0 + 670 = 670
Step 2: 670 + 670 = 1340
Step 3: 1340 + 670 = 2010
Step 4: 2010 + 670 = 2680
Step 5: 2680 + 670 = 3350

So, 670*5 = 3350