OK, let's work through this together. We're starting with 905 and we're going to multiply it by 6, which means we add 905 to itself 6 times.
Step 1: 0 + 905 = 905
Step 2: 905 + 905 = 1810
Step 3: 1810 + 905 = 2715
Step 4: 2715 + 905 = 3620
Step 5: 3620 + 905 = 4525
Step 6: 4525 + 905 = 5430

So, 905*6 = 5430