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# Why the value of "pi"is fixed for 22/7? Why not the any other value?

In most of the engineeirng subjects we are familiar with the parameter "pi"

Kaustubh Katdare • Sep 29, 2018

Interesting question. The PI (π) , represents the radio of the circumference of a circle to its diameter.

Now, if you draw a perfect circle and measure its circumference and diameter, they're going to be in the ratio 22/7; thus the value.

For all practical calculations, the value for calculations is set to 3.1415 (or just 3.14). However, be aware that the number itself is never ending.

So, to answer your question - it's the ratio that we get measurements of a circle.

Because Pi is endless. 22/7 is good enough for most purposes. 355/113 is much more accurate.

I just use 3.1416 for all engineering calculations. Easy to remember.

pi/4 is another figure appearing often.

0.7854 is the best value for this. Interestingly  7854 appear clockwise on all calculators and computer key boards so no memory is needed.

Kaustubh Katdare • Sep 29, 2018

PS: I'm actually very fascinated by the concept of Pi. A circle is a perfect geometric shape that I can visualise in mind. What boggles my mind is that if it's a perfect shape - then it had to be a rational number; but mathematically 22/7 ≠ 3.14...

How could that be possible? [Or am I just sleepy at the moment to think 'rationally'?]

@Kaustubh , I share your fascination for the circle. A curious fact about a circle is that every circle, atomic size or galaxy size and wherever in space, passes through the same two points at infinity!

Kaustubh Katdare • Sep 29, 2018

@Ramani sir - it's fascinating. I always imagined a 'line' as a series of atoms side-by-side; and the total length of the line would be equal to the sum of diameters of the atoms (it doesn't make sense; but why not imagine atoms as marbles). Did you imagine it any different?

Nothing very wrong with that except that the line will then have a thickness equal to the diameter of the atom. A line in mathematics has no thickness.

Another thing is that the number of points on a line is infinite. It is the same infinity for all lines of any length and kind, straight, curved or twisted.

It gets worse. The number points on any line is equal to the number of points in any area, and any solid.

However, interestingly there are infinities that have different sizes. Apparently there are three of them and only three.

George Gamov’s “One two three infinity” describes many of these fascinating facets of maths and science.