Before we had computers what did we do? Before computers we had human computers. People whose job was to do large calculations. A scientist back in 1700s wanted to make a mathematic model of Hill's orbit. He hired two of his friends (one of them a woman) to do the calculus and it still took five months to do all of it. People quickly realized that dividing the work is the key to better efficiency. For example a civil engineer in late 1700s and early 1800s wanted to write a 19 volume textbook series. First he and some of his friends divided all the calculation; then he hired 80 people to do the work, and it still took them 5 years to complete the job. In both first and second world wars, all sides used human computers for calculations regarding maps and weapons. Contrary to what you might think, these human computers were not at all experts at math and calculation. In fact some of them only had basic math skills or could not find other jobs. Women also had a considerable role in these calculations, and even, as stated above, one of the three people who modelled Hill's orbit was a woman. The source of all the information stated above is a book titled “When Humans Were Computers”. The author learned of his grandmother attending university and having a degree in mathematics by chance and this got him interested in learning more about calculation before the invention of computers.