Shopping, change and a budget

Last lesson, you added and subtracted money. A toy costs four dollars, and you pay with a five-dollar note. Five minus four is one, so you get one dollar back. This money is called change. Today, we find the total cost first, and then the change. Kavin buys bread for two dollars and sixty cents and noodles for one dollar and thirty cents. He pays with a five-dollar note. How much change does he receive? We must find Kavin's change. Kavin pays for the bread and the noodles together. So first, we find the total cost. Add the two prices in a column, with the decimal points lined up. Start with the cents. Zero plus zero is zero. Six plus three is nine. Two plus one is three. The total cost is three dollars and ninety cents. His change is five dollars minus the total cost. Write five dollars on top. It has no cents, so we write two zeros. Write the total cost below, not just one price. Zero minus zero is zero. Now the ten-cents. We cannot subtract nine ten-cents from zero ten-cents. Rename one dollar as ten ten-cents. Five minus one is four. Write ten ten-cents above the zero. Ten minus nine is one. Four minus three is one. Kavin receives one dollar and ten cents in change. If you have money to spend, find what is left in the same way.

Mei Ling buys eggs for three dollars and fifty cents and milk for one dollar and twenty cents. She pays with a five-dollar note. How much change does she receive? Try it first. Pause if you like. First, find the total cost. Zero plus zero is zero. Five plus two is seven. Three plus one is four. Then subtract the total cost from five dollars. Zero minus zero is zero. We cannot subtract seven ten-cents from zero, so we rename one dollar. Five minus one is four, and the ten ten-cents go above the zero. Ten minus seven is three. Four minus four is zero. Mei Ling receives thirty cents in change.

Ravi has eight dollars. He buys two packets of biscuits at one dollar and forty cents each and a bottle of juice for three dollars and ten cents. How much money does he have left? Try it first. Pause if you like. There are two packets, so we add their price twice. First, find the total cost. Zero plus zero plus zero is zero. Four plus four plus one is nine. One plus one plus three is five. Then subtract the total cost from eight dollars. Zero minus zero is zero. We cannot subtract nine ten-cents from zero, so we rename one dollar. Eight minus one is seven, and the ten ten-cents go above the zero. Ten minus nine is one. Seven minus five is two. Ravi has two dollars and ten cents left. Find the total cost first, then subtract it from the money you have.