Let's roll up our sleeves and solve this. We have 936 and we're going to multiply it by 13, essentially adding 936 to itself 13 times.
Step 1: 0 + 936 = 936
Step 2: 936 + 936 = 1872
Step 3: 1872 + 936 = 2808
Step 4: 2808 + 936 = 3744
Step 5: 3744 + 936 = 4680
Step 6: 4680 + 936 = 5616
Step 7: 5616 + 936 = 6552
Step 8: 6552 + 936 = 7488
Step 9: 7488 + 936 = 8424
Step 10: 8424 + 936 = 9360
Step 11: 9360 + 936 = 10296
Step 12: 10296 + 936 = 11232
Step 13: 11232 + 936 = 12168

So, 936*13 = 12168