OK, let's work through this together. We're starting with 378 and we're going to multiply it by 5, which means we add 378 to itself 5 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

So, 378*5 = 1890