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

So, 1*7 = 7