OK, let's work through this together. We're starting with 73 and we're going to multiply it by 7, which means we add 73 to itself 7 times.
Step 1: 0 + 73 = 73
Step 2: 73 + 73 = 146
Step 3: 146 + 73 = 219
Step 4: 219 + 73 = 292
Step 5: 292 + 73 = 365
Step 6: 365 + 73 = 438
Step 7: 438 + 73 = 511

So, 73*7 = 511