（2+4+6+8+… +196+198）-（1+3+5+… +195+197）

（2+4+6+8+… +196+198）-（1+3+5+… +195+197）

（2+4+6+8+… +196+198）-（1+3+5+… +195+197）=（2-1）+（4-3）+（6-5）+… +（198-197）=1+1+1+… +1=99．

How to do 134 times 67 times 67 times 67 minus 67

134x67x67x67-67
=2×67x67^3－67
=2x67^4-67
=67x(2x67^3-1)

The square of 67 minus the product of 134 times 27 plus the square of 27 (with a simple method)

67x67-134x27+27x27
=67x67-67x2x27+27x27【（a-b）^2=a^2-2ab+b^2 】
=（67-27）^2
=40^2
=1600
However, it seems that pupils have never learned [(a-b) ^ 2 = a ^ 2-2ab + B ^ 2]
This formula

The short story of Mathematics
The shorter the better

Archimedes, an ancient Greek scholar, died at the hands of Roman enemy soldiers who attacked Sicily (before he died, he was still in charge of "don't break my circle"). In memory of Archimedes, people engraved the figure of the sphere inscribed on the cylinder on his tombstone to commemorate his discovery that the volume and surface area of the sphere were two thirds of the volume and surface area of its circumscribed cylinder