the ones column. since i borrowed one from the tens column i am left with 1, so i need to borrow 1 from the hundreds column, that gives me 11-2; so i put a 9 in the tens column. now i am left with 5-3, so i put a 2 in the hundred column. i am left with 298.
it takes a bit more time...but if your child is having difficulty you can build a 10,000 chart, using 10- 1000's charts. it takes a bit to put this together.... we keep our 10,000 chart up all the time in the house. it comes in handy when we discuss how big or 