Houses and roads:

In a village of PlanetaPi, our friends want to connect the four pairs of similar houses, each with a pair of the same color .. Can you connect all four pairs so that there is no crossroads?

Note: Be careful, there are only two central houses that are not next to the wall. The path can not pass between the wall and the six houses attached to it.

Bibliography:
«Juegos Matemáticos». Derrick Niederman. Ed. Victor. Aprende y practica

Candles:

Last night, while studying, the bulb stopped working. I lit two candles immediately and continued working until they fixed the fault. The next day I wanted to find out how long did the blackout, but did not know when it started or when it ended. I only remember the first candle can be lit five hours and the second four hours.
How long did the blackout if the first candle had been four times longer than the second?.

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Mathematics culture

The Mayans:

The Mayans were a great civilization that had great mathematical and astronomical knowledge. There are big questions about this civilization and much of the knowledge of their culture were destroyed for fear of higher knowledge, but knew the zero? How calculated? Did accurately measure time? You reviewer, …

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