Sure thing, let's get straight to it. We start with 387 and we're going to multiply it by 10, which means adding 387 to itself 10 times.
Step 1: 0 + 387 = 387
Step 2: 387 + 387 = 774
Step 3: 774 + 387 = 1161
Step 4: 1161 + 387 = 1548
Step 5: 1548 + 387 = 1935
Step 6: 1935 + 387 = 2322
Step 7: 2322 + 387 = 2709
Step 8: 2709 + 387 = 3096
Step 9: 3096 + 387 = 3483
Step 10: 3483 + 387 = 3870

So, 387*10 = 3870