A shopkeeper tells you milk costs 1,247 shillings. You tell your friend "about 1,250 shillings." Congratulations you just rounded off a number! Rounding is one of the most practical mathematics skills in everyday life: estimating distances, budgets, quantities, and time all rely on it. But there are specific rules that determine whether you round up or down and getting them right matters in engineering, medicine, and science. Today we master those rules so your estimates are always smart and defensible. Ready to round things up and sometimes down? Let's go!