Wearing his Secretary of Defense hat, Elliot Richardson gave Congress the other day a fascinating glimpse into the mathematics of saving the hearts and minds of remote peoples from whatever our bombers save them from when they bomb their countries.

During one quarter of this year (February, March, April), he said, the United States dropped 145,000 tons of bombs on Cambodia and Laos.

Population of the two countries is about 10 million persons.

Changing tons to pounds, we begin to see light. Territory containing 10 million people has been struck with 290 million pounds of bombs, or, to put it another way, the United States has been bombing at the rate of 29 pounds per person per quarter.

Extrapolating over a full year, we get a more useful mathematical formulation; to wit, that the United States is bombing the average Laotian/Cambodian at the rate of 116 bomb pounds per year.

The interesting question then arises, What is the weight of the average Laotian/Cambodian?

Here we lack data. We know them to be small people physically. We can only guess at what proportion of them is too young to have attained adult weight. Conceding these data deficiencies, it is still not unreasonable to hypothesize that our average Laotian/Cambodian weighs 87 pounds - or three-quarters of the annual bomb poundage used by the United States to save his heart and mind.

Secretary Richardson suggested that the bombing has done its job (which is to preserve the Government of a man named Lon Nol) and says it must go on in order to continue preserving this Government. Thus, for those of us interested solely in the mathematics of the thing, Mr. Richardson may fairly be said to have stated the proposition that the present bombing level is sufficient for the saving of hearts and minds.

If so, then we may state a general mathematical formula for determining the bomb poundage the United States will have to drop to save the hearts and minds of any given nation.

This formula is: HM = (4W/3)P, where HM represents hearts and minds, W represents weight of the average body containing the heart and mind to be saved and P represents total population of the bombed country.

Example: Suppose it is necessary to save the hearts and minds of Italy. How many pounds of bombs will we need? To get the answer we multiply the average Italian's weight (111 pounds) by 4 and divide the result (444) by 3, which gives us the hearts-and-minds-winning factor number, 148.

To save the hearts and minds of Italy we would have to drop 148 pounds per year per Italian, of whom there are about 55 million. This means we would have to drop 8.14 billion pounds of bombs or, to put it more manageably, about 4 million tons.

"All very well," the taxpayer will say, "but what will it cost me?" Here Mr. Richardson's figures are helpful.

The 63,000 tons dropped on Laos in three months he reported, cost $99.2 million, or $1,574 per ton.

In Cambodia 82,000 tons were dropped at a cost of $150.5 million, or $1,945 per ton.

In short, it costs 97 cents a pound to bomb Cambodia, but only 79 cents a pound to bomb Laos.

Of the two countries, Cambodia is relatively more advanced economically and has much the larger population. Thus, it appears that per-pound bombing cost must increase in proportion as size and economic complexity of the target country increases.

The bombing of Italy, which is much more advanced than Cambodia and much more populous, might cost as much as $2.50 a pound. At this price the 4 million tons needed to save Italy's hearts and minds for one year would cost slightly over $20 billion. Expensive perhaps, but who would say it is not worth it to save Venice for the free world?

These figures may improve taxpayer morale, for they give a clear idea of the useful tasks performed with the money we pay our Government.

If, for example, you have paid taxes of $1,000, you may very reasonably tell yourself that your contribution has made it possible to drop 1,266 pounds of bombs (at 79 cents per pound) on Laos, thereby saving the hearts and minds of 10 and 53/58ths Laotians for a whole year. (It takes 116 bomb pounds per year, remember, to save a single heart and mind there.)

With figures like these, you do not have to ask your country what it will do for you. You can tell Laos and Cambodia what you have done for them.