Question

What was Eniac-1 actually used for?

Answer 1

ENIAC 1 specifically was developed to do large class of numerical problems. The main objective for this discovery was for use in the US Army, for calculations of various weapons of artillery and others.  At that time, Jon von Neumann was a mathematician working on hydrogen bombs, and used this Computer for his calculations of the bomb. 

Answer 2

Eniac-1 was used for calculating hard and long arithmetical problems.