Article: The abacus was initially used for arithmetic tasks. The Roman abacus was used in Babylonia as early as 2400 BC. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money.

Question: When was the Roman abacus first used?
Ans: 2400 BC


Article: A test given to new students by Stanford University Music Professor Jonathan Berger showed that student preference for MP3-quality music has risen each year. Berger said the students seem to prefer the 'sizzle' sounds that MP3s bring to music.

Question: Data showed that students' preference for MP3 quality music followed which trend?
Ans: risen each year


Article: In 2012, the city contained a total of 594 high-rise buildings, with 8 under construction, 71 planned and 39 at proposal stage making the city's skyline the second largest in Australia. The CBD is dominated by modern office buildings including the Rialto Towers (1986), built on the site of several grand classical Victorian buildings, two of which — the Rialto Building (1889) designed by William Pitt and the Winfield Building (1890) designed by Charles D'Ebro and Richard Speight — still remain today and more recently hi-rise apartment buildings including Eureka Tower (2006), which is listed as the 13th tallest residential building in the world in January 2014.

Question: Which building was listed as the 13th tallest residential building in the world in January 2014?
Ans: Eureka Tower


Article: Von Neumann raised the intellectual and mathematical level of economics in several stunning publications. For his model of an expanding economy, von Neumann proved the existence and uniqueness of an equilibrium using his generalization of the Brouwer fixed-point theorem. Von Neumann's model of an expanding economy considered the matrix pencil  A − λB with nonnegative matrices A and B; von Neumann sought probability vectors p and q and a positive number λ that would solve the complementarity equation

Question: What did von Neumann prove with his model of expanding economy?
Ans:
uniqueness of an equilibrium using his generalization of the Brouwer fixed-point theorem