OK, let's work through this together. We're starting with 635 and we're going to multiply it by 3, which means we add 635 to itself 3 times.
Step 1: 0 + 635 = 635
Step 2: 635 + 635 = 1270
Step 3: 1270 + 635 = 1905

So, 635*3 = 1905