MATH PUZZLE: Can you replace...

An old man goes into Victoria's Secret and tells the sales-person behind the counter he needs a present for his wife. "See," explains the man, "It is my fiftieth wedding anniversary and I would like to get something pretty to surprise the little lady, if you know what I mean." When he gets home, his wife asks with a scowl on her face, "Where have you been?" "Surprise," says the old man and hands her a sexy tiny teddy. The wife rips it from his hand and takes it to the bathroom to try it on. She struggles to make it fit, but it is two sizes too small. She take a long time in the bathroom and hopes her husband will lose interest and fall asleep because it is getting late into the evening. Finally she emerges from the bathroom with all the lights out. She is completely nude and pretends to model it in front of him. Her husband, still sitting up, squinting to try and see finally says, "For as much money I spent on it, they could of at least ironed out the wrinkles."