30/100 = 30%
A value like 30% shows up in everyday life when a store advertises a discount, a weather report gives the chance of rain, or a survey shares how many people chose an option. What it means depends on what the whole amount is.
To picture it quickly, imagine 10 equal pieces and shade 3 of them. That gives you a rough sense of the size without needing to calculate anything.
A common point of confusion is forgetting what the percentage is based on. For example, a 30% discount takes 30% off the original price, not necessarily off a price that has already been reduced.
