Why should I learn mathematics ?

This is an interesting question: you get very different answers, if you ask a technician, a scientist, your uncle, your mother, or your teachers.
Anyway, it is a (questionable !) fact, that you must learn more or less mathematics in almost each education. In a course for carpenters I gave the following answer to this question --- starting with a problem, giving a solution to the problem causing more detailed questions (typically ;-)) and ending up with some unexpected conclusions:
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Now, let us start with the problem:
Given a wooden beam with a square cross-section of length q=20cm, take this beam (of sufficient length) to build a cube of side length s=100cm like that:
picture of the cube built from the beam
If you start cutting the edges for the cube, you will recognize, that not all of them need to be 100cm long. Some of the edges will be shorter because of the intersections at the corners of the cube. There are many possibilities to assemble the edges at the corners such that the side length of the cube is 100cm everywhere:

picture of first version for the corners
Fig.2
picture of the second version for the corners
 Fig.3
picture of the third version of corners
 Fig.4

After having built the cube, you can measure, how much of the length of the beam you actually needed (it is much less then 12m for the 12 edges, even forgetting the wood becoming sawdust -- we actually will neglect the wideness of the 12 cuts in the sequel for simplicity reasons !). As a human being, most likely, you will have estimated, or even calculated, the length of the beam you require in advance; in order to go sure for the outcome of your work before you waste your efforts.
Now we want to lure you into using ISAC you are visiting just now: Please, click one of the following calculations (even if you would build the cube in a another way):

calculate Fig.2 calculate Fig.3 calculate Fig.4