Let's roll up our sleeves and solve this. We have 549 and we're going to multiply it by 7, essentially adding 549 to itself 7 times.
Step 1: 0 + 549 = 549
Step 2: 549 + 549 = 1098
Step 3: 1098 + 549 = 1647
Step 4: 1647 + 549 = 2196
Step 5: 2196 + 549 = 2745
Step 6: 2745 + 549 = 3294
Step 7: 3294 + 549 = 3843

So, 549*7 = 3843