Subtracting 10s using place value

right here we have 65 blocks and you can count them if you like but we can represent them with the number 65 by writing a six in the tens place we're literally saying that we have six tens and this is a ten this is the ten this is another ten this is another ten this is a ten this is a ten and this is a ten we have six groups of ten and that makes sixty and then we have five ones five do that orange color and then we have five ones and you see them right here one two three four five so now let's do something interest right that down again just to emphasize it so we can write down that 65 65 is equal to six tens six tens plus five ones plus five ones now let's do something interesting let's start with 65 so let me write that down again so I'm going to start with 65 in trouble changing colors we're going to start with 65 and I'm going to subtract I'm going to subtract 40 I'm going to subtract 40 from that so what am I really doing here well I'm starting with 65 I'm starting with this and I'm subtracting four tens and zero ones so let's subtract four tens from here so let's subtract one two three four so I took away four of the tens so how many tens do I have left over well I have left over two tens so this is going to be equal to two tens and how many ones do I have well I still have five ones so it's still I still have five ones and that makes sense add five ones I took away zero ones so I'm still going to have five ones and so what is this going to be equal to so we can write 65 65 minus 40 - 40 is let me do that I want to do the ones in that orange color - 40 is equal to another way of saying - tens is by putting a two in the tens place and a and then we have five ones of five in the ones place so two tens plus 5 ones or 25