Let's roll up our sleeves and solve this. We have 680 and we're going to multiply it by 5, essentially adding 680 to itself 5 times.
Step 1: 0 + 680 = 680
Step 2: 680 + 680 = 1360
Step 3: 1360 + 680 = 2040
Step 4: 2040 + 680 = 2720
Step 5: 2720 + 680 = 3400

So, 680*5 = 3400