Sure thing! We've got 668 and we're gonna multiply it by 6. That's the same as adding 668 to itself 6 times.
Step 1: 0 + 668 = 668
Step 2: 668 + 668 = 1336
Step 3: 1336 + 668 = 2004
Step 4: 2004 + 668 = 2672
Step 5: 2672 + 668 = 3340
Step 6: 3340 + 668 = 4008

So, 668*6 = 4008