Answer:
The use of the abacus was expanded and refined.
Explanation:
The abacus was invented during the Yuan Dynasty which lasted between 1206AD till 1368AD and then it was expanded and refined by the Ming Dynasty (1368AD-1644AD).
There have been archaeological proof of this as the writings of Tao Zongyi describes in his book that the new servants, unlike the older and more experienced ones were "just like abacus heads" and that they would not move unless they were made to move. This bears credence to the fact that the abacus was already widely used then.
An abacus was used to count numbers.
Hitler suggests that they needed Ethnic cleansing
The government helped the railroad industry is by granting land to the railroad companies
Migrants workers found job in San Joaquin Valley in California. This valley in California had a good stable climate which was good for farming. And because of route 66, they were straightly lead there from dustbowl in order to look for jobs.
