OK, let's work through this together. We're starting with 915 and we're going to multiply it by 3, which means we add 915 to itself 3 times.
Step 1: 0 + 915 = 915
Step 2: 915 + 915 = 1830
Step 3: 1830 + 915 = 2745

So, 915*3 = 2745