Source, in full
Often attributed to Nixon, this is a slight misquote of a second-hand account of what he said. "In the fall of 1972 President Nixon announced that the rate of increase of inflation was decreasing. This was the first time a sitting president used the third derivative to advance his case for reelection." Hugo Rossi:" Mathematics Is an Edifice, Not a Toolbox". Notices of the American Mathematical Society, 1996. Vol 43, No 10, pg 1108.