Mensa Challenge Bonus (Week 1)
I got a few complaints that the first puzzle was much too easy. That was sort of the point. Introduce something nice and simple and work our way up from there. Apparently the masses are demanding more difficult challenges.
I present today a bonus Mensa challenge that only 20% of people get correct on first blush. Let us see how people do on this puzzle.
Your friend invites you to a dinner party at their new house. Instead of an actual address your friend gives you the following information: “All the houses on my side of the street are numbered consecutively in even numbers. There are six houses on my side of my block and the sum of their numbers is 9870. You don’t know which block I live on, and it is a long street, but I will tell you that I live in the lowest number on my side of the block. What’s my number?”
I will mention that this is a slight modification on a common SAT question. So while I knew how to solve it immediately it was only because of having dealt with similar problems frequently.
Good luck.
Your friends street number is 1640. There are probably a few ways to do this but you can turn it into a simple algebra problem. Assuming that your friend’s street number is X and that all of the houses on her block sum up into 9870. This is can be written as follows.
Since each house number is dependent on the initial house number you can easily create an equation with only one unknown. Thus making it a simple case of algebra to solve for the answer.
This is the beauty of algebra. It is a very fixed and conscise descriptor of English that follows very formal rules. It is possible to “think this out” without using algebra but the complexity that natural language conceals the answer illustrates exactly why algebra is such an elegant mathematical tool.
And yes I am a bit of a math nerd.