Sure thing, let's get straight to it. We start with 905 and we're going to multiply it by 4, which means adding 905 to itself 4 times.
Step 1: 0 + 905 = 905
Step 2: 905 + 905 = 1810
Step 3: 1810 + 905 = 2715
Step 4: 2715 + 905 = 3620

So, 905*4 = 3620