Δ meaning in mathematics I am reading an article for percentage calculations... "This means that if you want to calculate the price change in a given stock, you subtract the current price from yesterday's closing price and then divide by yesterday's closing price, and then, finally, multiply by 100 to express that number as a percentage." ΔPrice / YesterdayClose * 100 and I am wondering what is the meaning of `Δ`

$\Delta$ means "Change in". So if $P=$price, $\Delta P = P_{start} - P_{end}$