Government head-counters almost ruined President Reagan's breakfast yesterday morning.

The people who keep track of the number of government employes reported that federal employment in the metro Washington area had crept up 111,814 jobs from November to December of last year.

While it would have done wonders for the economy here, unfortunately it is not true.

The corrected figure of about 1,600--which will be coming out today--shows that metro Washington is experiencing a population mini-explosion among its civil servants, but not to the extent that it will give critics of big government any more ulcers than they aleady have.

Federal employment in metro Washington will show a jump in June when the metro Washington area becomes the metro Washington-Arlington area. At that time the Maryland counties of Calvert and Fairfax will be joining us, as will Stafford County, Va., plus the cities of Manassas and Manassas Park.

Actually, the number of federal employes here (as of December 1982) is 346,878. That is an increase of about 1,600 from the previous month, and a rise of 3,562 from December 1981. What it means is that metro Washington's federal population is heading back to where it was before President Reagan started riffing government workers.

Since the Reagan administration took office, nearly 3,000 employes here have been fired for economy reasons.

There was a moment of panic yesterday when the Office of Personnel Management--which makes monthly headcounts of the federal establishment--discovered its error. It was feared, for a moment, that the government had committed a terrible breach of security and had included the top secret number of people who work in top secret agencies in the area.

Neither agency is included.

Nearly 16 of every 100 federal workers now live in the new metro Washington area. Before the new cities and counties were annexed into the Washington-Arlington complex, about 13 percent of the federal workforce was employed here.

Worldwide, the government (as of December 1982) has 2,861,937 employes, including about 63,000 non-citizens employed overseas.

The biggest increase in federal employment last year (from December 1981 to December 1982) came in the Defense Department. Army, Navy and Air Force, in that order, took on most of the 7,400 new civilian federal workers hired.

Agriculture Department (down 2,269) and the Tennessee Valley Authority (down 2,269) were the biggest losers during the period.

But overall, according to the government, the total number of federal workers increased by only 1,206 during the past year. That means that a lot of non-Defense agencies were shrinking, while civilian employment in Defense was going up. So if you think you are confused by the up-down nature of federal employment, welcome to the club. Sometimes even the official keepers of the head count can't tell up from down.