Let's roll up our sleeves and solve this. We have 638 and we're going to multiply it by 11, essentially adding 638 to itself 11 times.
Step 1: 0 + 638 = 638
Step 2: 638 + 638 = 1276
Step 3: 1276 + 638 = 1914
Step 4: 1914 + 638 = 2552
Step 5: 2552 + 638 = 3190
Step 6: 3190 + 638 = 3828
Step 7: 3828 + 638 = 4466
Step 8: 4466 + 638 = 5104
Step 9: 5104 + 638 = 5742
Step 10: 5742 + 638 = 6380
Step 11: 6380 + 638 = 7018

So, 638*11 = 7018