Let's roll up our sleeves and solve this. We have 668 and we're going to multiply it by 11, essentially adding 668 to itself 11 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
Step 7: 4008 + 668 = 4676
Step 8: 4676 + 668 = 5344
Step 9: 5344 + 668 = 6012
Step 10: 6012 + 668 = 6680
Step 11: 6680 + 668 = 7348

So, 668*11 = 7348