This task involves creating questions from a given passage that involve some kind of complex reasoning (including numerical reasoning).
The generated questions must require looking at more than one part of the passage to answer. Try to use a variety of reasoning types in your questions (some of the sample reasoning types are illustrated in the 'positive examples' field) and also have a variety of answer types (spans, numbers, dates). A span is a continuous phrase taken directly from the passage or question. In such questions, the answer spans are recommended to be five words. Questions with answer type "number", are expected to start with "How many". For instance, "How long did an event last?" can be phrased as "How many years did an event last?". To increase diversity, try to create more questions for which the answer will be multiple spans. Please create questions that require AT LEAST 2 arithmetic operations as illustrated in the 'positive examples' field. You are encouraged to try DIFFERENT COMBINATIONS of operations and not just limit to the combinations shown in those examples. The more challenging questions you create, the better it is.

Passage: The fortifications of Mdina are a series of defensive walls which surround the former capital city of Mdina, Malta. The city was founded as Maleth by the Phoenicians in around the 8th century BC, and it later became part of the Roman Empire under the name Melite. The ancient city was surrounded by walls, but very few remains of these have survived. The city walls were rebuilt a number of times, including by the Byzantine Empire in around the 8th century AD, the Arabs in around the 11th century, and the Kingdom of Sicily in the medieval period until the 15th century. Most of the extant fortifications were built by the Order of Saint John between the 16th and 18th centuries. The city has withstood a number of sieges, and it was defeated twice - first by the Aghlabids in 870 and then by Maltese rebels in 1798. Today, the city walls are still intact except for some outworks, and they are among the best preserved fortifications in Malta. Mdina has been on Malta's tentative list of UNESCO World Heritage Sites since 1998.
At least how many times were the city walls rebuilt?