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Re-engineering Math

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Add a percentage is a multiplication

Add a percentage, say 5% is not making an addition. It is a multiplication by (1+5/100). You may also multiply by 5, divide by 100, and then add the result to the original amount.

For instance, the VAT of 20% multiplies the taxes free amount by 1.2, or else adds 20% of the taxes free amount to itself.

That's why the VAT amount of 20% is NOT 20% of the price, as the price is the taxes included amount. To obtain the VAT amount from the price, you must first DIVIDE the price b...

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The A4 format as a division of a surface of 1 square meter

We all know the A4 format as a rectangle of 21x29.7 cm. But who knows that it is a mathematical construction that implies an A0 format and subsequently A1, A2 and A3?

The basis is the A0 format, a rectangle with a 1 square meter area, with particular proportions. We shall find the ration of the length L0 over width l0 when we construct the A1 format.

The A1 format is half a A0 format. More precisely, its length L1 is the width l0 of the A0 format, and its width l1 is half t...

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Neil Armstrong looses much weight on the moon!

In everyday language, we say that the weight of an object is the number of grams of kilograms it… weights!

But the physicians call the number of grams or kilograms the "mass", the weight being the force of gravity induced by the earth mass: P=mg, in Newtons if m is in kilograms and g in meters per seconds to the power 2.

What does that holly mess mean? Are we completely wrong when we speak of the number of kilograms as of the weight?

As a matter of fact, the weight ...

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