Sensor size of P&S vs DSLR?

If I go to Nikon's site and look at the sensor specs I can see that a DX format sensor is 23.6x15.8mm and an FX format is 24x36mm, but if I look up some P&S specs on sensors I see 1/1.7" or 1/2.5" for the sensor "size". So, I do know math and can divide 1 by a number, is this the diagonal measurement of the sensor? Therefore the hypotenuse of a right triangle? I'm just curious to put it in more of an apples to apples kind of comparison. We keep making statements like "DSLR sensors are 15 times the size of P&S sensors", but I was just wanting the number to back up the statement.