Input: Translation
Comparison of a back-translation with the original text is sometimes used as a check on the accuracy of the original translation, much as the accuracy of a mathematical operation is sometimes checked by reversing the operation. But the results of such reverse-translation operations, while useful as approximate checks, are not always precisely reliable. Back-translation must in general be less accurate than back-calculation because linguistic symbols (words) are often ambiguous, whereas mathematical symbols are intentionally unequivocal.

What is sometimes used to check the accuracy of a translation?
Output: Comparison of a back-translation with the original text

Input: Montana
The Yellowstone River rises on the continental divide near Younts Peak in Wyoming's Teton Wilderness. It flows north through Yellowstone National Park, enters Montana near Gardiner, and passes through the Paradise Valley to Livingston. It then flows northeasterly across the state through Billings, Miles City, Glendive, and Sidney. The Yellowstone joins the Missouri in North Dakota just east of Fort Union. It is the longest undammed, free-flowing river in the contiguous United States, and drains about a quarter of Montana (36,000 square miles (93,000 km2)).

Where does the Yellowstone meet the Missouri river?
Output: North Dakota

Input: Mexico City
The National Autonomous University of Mexico (UNAM), located in Mexico City, is the largest university on the continent, with more than 300,000 students from all backgrounds. Three Nobel laureates, several Mexican entrepreneurs and most of Mexico's modern-day presidents are among its former students. UNAM conducts 50% of Mexico's scientific research and has presence all across the country with satellite campuses, observatories and research centres. UNAM ranked 74th in the Top 200 World University Ranking published by Times Higher Education (then called Times Higher Education Supplement) in 2006, making it the highest ranked Spanish-speaking university in the world. The sprawling main campus of the university, known as Ciudad Universitaria, was named a World Heritage Site by UNESCO in 2007.

How many students attend UNAM?
Output: 300,000

Input: Late Middle Ages
With the financial expansion, trading rights became more jealously guarded by the commercial elite. Towns saw the growing power of guilds, while on a national level special companies would be granted monopolies on particular trades, like the English wool Staple. The beneficiaries of these developments would accumulate immense wealth. Families like the Fuggers in Germany, the Medicis in Italy, the de la Poles in England, and individuals like Jacques Coeur in France would help finance the wars of kings, and achieve great political influence in the process.

Which economic associations gained power in the towns?
Output:
guilds