Addition I

[Music] Billy Thompson is opening his bank he's been saving to buy a set of paints for school and the baseball bat does he have enough money to buy those things he doesn't really have the paint box yet but let's pretend it's here how much do the paints cost 65 but Billy doesn't have the paints yet how about the bat how much does it cost $129 and Billy doesn't have the bat now either let's write down these numbers for the paints 65 or 65 pennies and for the bat $129 or 129 pennies but how much money does Billy have he has $1 that's the same as 100 pennies and a half doll or 50 pennies and a quarter or 25 pennies and 1 2 3 4 dimes or 40 pennies and 1 2 3 4 5 6 7 8 pennies now Billy can add just a minute Billy just how did you add arrange your money on the floor and with the numbers we'll see how adding works here are eight pennies let's put down eight and here are four dimes how shall we put this down to write this number we need two places here's a four to stand for the four dimes and now we'll need a zero as a placeholder in the unit's place we'd better move the dimes and pennies into their places too one place will be for pennies call it the unit's place and this place will be for dimes call it the 10 place place but let's study our numbers a little 1 2 3 4 5 6 7 8 9 these numbers belong in the unit place but 10 takes up two places this one means 11 10 and this zero means no units now 110 and one unit 11 110 and 2 units 12 110 and 3 units 13 and so on so now we all know that this number means 4 10 and no units 40 we put down the number 40 to stand for four dimes now what number should we put for the rest of Billy's money here's a quarter let's change it to Penny and dimes so we can add we'll change it to pennies first how many pennies do we have let's pile them up and see here are five pennies to add to the other pennies and two piles of 10 pennies each a dime is the same as 10 pennies and a quarter is the same as five p and two dimes what number should we put down five units and and two 10 25 now do you know how many dimes make a half dollar that's right five so what do we put to stand for the half dollar five dimes and no pennies 5 tens and no units and now the dollar what should we put for the dollar do you know well suppose we change the dollar to pennies what a lot of pennies let's pile them up by tens now 10 piles with 10 pennies in each pile if we change them to dimes we'll have 10 dimes and 10 dimes are the same as $1 now there are no pennies so we'll put zero in the units place there are no dimes so we'll put zero in the 10's place then a one in the hundred's place gives us the number to stand for $1 100 and there are the numbers to stand for Billy's money now we're ready to add the numbers on the floor just the way Billy added the same numbers on the Blackboard we'll start from the top and add the units first five units and eight units five pennies and 8 pennies that makes 13 pennies doesn't it but we can't put 13 in the unit's Place 13 takes up two places 13 really means 110 and three units one dime and three pennies we'll put three in the unit's place and and we have one more dime to add to the other dimes so above the 10's Place let's put down one now we'll add the tens 1 10 and 5 T and 2 10 and four tens one dime and five dimes six dimes and two 8 dimes and four 12 dimes we can't put 12 12 in the 10's Place 12 takes up two places so we'll change 10 of the dimes to $1 then there are two dimes left and we'll put two in the 10's place now we have one more dollar to add to the other dollar and above the hundred's place one more hundred to add to the other 100 100 and 100 one do and one more dollar $2 so we'll put two in the hundred's place and that's the way to add that's the way Billy adds now Billy wants to check to make sure he didn't make a mistake he added from the top before so this time Billy will add from the bottom 8 13 1 5 7 12 1 2 and now Billy has two hunds and two t and three units that's the same as 223 pennies is that enough to buy the paints and the bat see if you can add with Billy four belongs in the unit's Place nine in the 10 place and one in the hundreds place what is the answer and how do we check our adding that's right add from the bottom up 194 just what we found adding the other way and Billy knows that 223 is more than the price of both the paint and the bat so he can buy them both and he'll have some money left uhoh better pick up the money now Billy can can't wait to have both the paints and the backat he added and he found out that he has enough money to buy them both and we found out how to add we know that this is the unit's place and this is the 10's place and this is the hundred's place and 10 units are the same as 110 addition is easy oh