OK, let's work through this together. We're starting with 587 and we're going to multiply it by 7, which means we add 587 to itself 7 times.
Step 1: 0 + 587 = 587
Step 2: 587 + 587 = 1174
Step 3: 1174 + 587 = 1761
Step 4: 1761 + 587 = 2348
Step 5: 2348 + 587 = 2935
Step 6: 2935 + 587 = 3522
Step 7: 3522 + 587 = 4109

So, 587*7 = 4109