OK, let's work through this together. We're starting with 429 and we're going to multiply it by 3, which means we add 429 to itself 3 times.
Step 1: 0 + 429 = 429
Step 2: 429 + 429 = 858
Step 3: 858 + 429 = 1287

So, 429*3 = 1287