Math Is Fun Forum

I just remembered a question asked to me when I participated in a quiz when I was 14 :

A three digit number is written on a window glass,
the difference between the number and as it can be seen from the other side is 693,
what's the number?

T R U C E !!!!!!!!!!!!!!!!

Hi Helen,
I don't know what you mean by pie questions and pie formula.
If you mean pi, I shall explain to you.
Pi is a Greek alphabet used to represent the ratio of the circumference of a circle to its diameter, which is always a constant.
Pi is taken as 3.14 or 22/7, as an approximation,
but the actual value of pi is
3.14159265358979323846264338327950288.......it goes on and on.
The area of a circle of radius 'r' is
pi*r²  and its circumference is 2*pi*r
Similarly, the volume of a sphere of radius'r' is
4/3*pi*r³  and its area is 4*pi*r² .
Pi is also an angle of 180 degrees.
Therefore, pi/2 would be 90 degrees and pi/4 45 degrees.
If you have any specific doubt, you can post in this forum.

Great! That's a big compliment, Thank you

Thank you, Admin, for the neat graph.

Thank God, they were not successful!

Which is greater?
Cos (Sin A) or Sin (Cos A)?

Hi, I love pi! Welcome to the forum!
Trying to find the square root of 0 using logarithms is not possible
as log 0 is not defnined. This is because any number raised to any number cannot be 0. That includes 0.
The square root, cube root, fourth root etc, of 0 IS 0.
This is because
0² = 0
0³ = 0
0^4 = 0 and so on.
Any nth root of 0 is 0, the only condition being n ≠ 0.
This follows from the fact that
if a^b = c, then bth root of c = a.
The birth of imaginary numbers is, indeed, interesting.
I had read somewhere that imaginary numbers have practical applications too!

And thats the only one I remember!

I would be wasting close to 33 years of my life if i did (the American Billion), assuming I don't sleep!

There are two types of decimals:- Terminating and recurring.
A number like 12.5 or 1.25 or 3.75 is a terminating decimal.
On the other hand, sometimes, you have numbers like 0.33333333333333.................,
0.166666666666.....................,
1.6666666666666 etc which are called recurring decimals.
For example, 1'/2 or 1/8 is a terminating decimal.
1/3, 5/6 etc are recurring decimals.
I was talking about how recurring decimals are convereted into rational numbers (that is, fractions).
If that is clear, look at the following illustration.
How do we convert 2.166666666666.............. into a rational number?
Let x = 2.16666666666666666............
10 x = 21.66666666666666666..........  ----------(I)
100x = 216.6666666666666666.........  ----------(II)
Subtracting (I) from (II),
90x = 195,
x = 195/90 or 13/6.
Now, have I made myself clear?

As simple as that!
But you would have to remember
(1) A second is a billion (US) nanoseconds but not a billion (UK) nanoseconds.
and
(2) An American Gallon is different from a gallon in UK