OK, let's work through this together. We're starting with 378 and we're going to multiply it by 11, which means we add 378 to itself 11 times.
Step 1: 0 + 378 = 378
Step 2: 378 + 378 = 756
Step 3: 756 + 378 = 1134
Step 4: 1134 + 378 = 1512
Step 5: 1512 + 378 = 1890
Step 6: 1890 + 378 = 2268
Step 7: 2268 + 378 = 2646
Step 8: 2646 + 378 = 3024
Step 9: 3024 + 378 = 3402
Step 10: 3402 + 378 = 3780
Step 11: 3780 + 378 = 4158

So, 378*11 = 4158