Let's roll up our sleeves and solve this. We have 671 and we're going to multiply it by 9, essentially adding 671 to itself 9 times.
Step 1: 0 + 671 = 671
Step 2: 671 + 671 = 1342
Step 3: 1342 + 671 = 2013
Step 4: 2013 + 671 = 2684
Step 5: 2684 + 671 = 3355
Step 6: 3355 + 671 = 4026
Step 7: 4026 + 671 = 4697
Step 8: 4697 + 671 = 5368
Step 9: 5368 + 671 = 6039

So, 671*9 = 6039