Unitary Computations of factorials

Novel phosphorothioates represented by the formula, wherein R1 is a chlorine or bromine atom, R2 is methyl or ethyl group and R3 is a chlorine or bromine atom or nitro group, which have a low toxicity to men and beasts as well as fishes, no phytotoxicity to crops, excellent fungicidal effect on injurious epidemic soil fungi in agriculture, horticulture and the like, and a wide range of uses for prevention of soil epidemics to effect the growth promotion of crops.