Let's roll up our sleeves and solve this. We have 25 and we're going to multiply it by 5, essentially adding 25 to itself 5 times.
Step 1: 0 + 25 = 25
Step 2: 25 + 25 = 50
Step 3: 50 + 25 = 75
Step 4: 75 + 25 = 100
Step 5: 100 + 25 = 125

So, 25*5 = 125