Sure thing! We've got 909 and we're gonna multiply it by 4. That's the same as adding 909 to itself 4 times.
Step 1: 0 + 909 = 909
Step 2: 909 + 909 = 1818
Step 3: 1818 + 909 = 2727
Step 4: 2727 + 909 = 3636

So, 909*4 = 3636