OK, let's work through this together. We're starting with 945 and we're going to multiply it by 3, which means we add 945 to itself 3 times.
Step 1: 0 + 945 = 945
Step 2: 945 + 945 = 1890
Step 3: 1890 + 945 = 2835

So, 945*3 = 2835