NOBODY EVER SAID that counting the number of people in the country was easy. But does it have to be this hard? Given what Congress and the courts seem to be doing, every large community (not to mention the 50 states) could come out of the 1980 census with several figures: 1) the number of people actually counted by the Census Bureau, 2) that number adjusted upward for undercounting of blacks and Hispanics or 3) adjusted downward to eliminate illegal aliens or 4) adjusted upward for one and downward for the other.

Which of these numbers should then be used to divide the seats in the House of Representatives among the states? Should the same figure be used by the states in reapportioning their legislatures? By local governments in drawing new districts for boards of supervisors or city councils? Which number is the right one for calculating federal aid to the states or state aid to localities?

The census, in short, is a mess -- and every day it's getting messier. The proposed congressional interference -- directing the Census Bureau not to report its figures for reapportionment purposes because illegal aliens had been counted -- was bad enough. But the order of a federal judge in Detroit that all the census numbers now be "adjusted" for undercountin of minorities complicates things beyond reason.

The government almost has to appeal that ruling. If it doesn't, there will be endless haggling, in court and out, over the validity of the "adjustments" and how they should be used. If it does appeal, considerable time will pass before higher courts can rule.

While time is not yet critical for uses of the census data by the federal government, it is getting short for a few states. The Virginia General Assembly, for example, is under a state constitutional mandate to reapportion itself in 1981. To do that before the 1981 elections -- a June primary and a November general election in which all the seats in the House of Delegates are up -- the legislature needs the census numbers in January. But which numbers? And what if the numbers aren't ready? Should the General Assembly postpone the primary in hopes of reapportioning at a special session later in the year?Or should it simply give up trying to do the job until after November?

The only likely results of this turmoil are much litigation and delay in the shifts of political power that the census and reapportionment are designed to compel. It is worth recalling that Congress never got around to redistributing seats in the House after the 1920 census and that some state legislatures never reapportioned fairly until the courts forced them to. The temptation is great for any legislature to delay reapportionment if it can find a plausible excuse. The disputes over the Census Bureau's numbers are well on their way to providing not only an excuse but also, unfortunately, a solid justification.