Intereting Posts

Measure theoretic entropy of General Tent maps
Generalizing Ramanujan's 6-10-8 Identity
Matlab Recursion Loop
Convergence of Sequences
What's special about $C^\infty$ functions?
Describe all integers a for which the following system of congruences (with one unknown x) has integer solutions:
If $a$ is even and $b$ is odd then $\gcd(2^{a}+1,2^{b}+1)=1$
A sequence of random variables which converges in distributon converges “to” some random variable
Card probability problem
Reference Book on Special Functions
Josephus' Puzzle Basic Java with some basic math.
let ${v_1}, {v_2} $ be orthonormal basis for subspace $W$. Prove that if $z$ is a vector in $W$, then
How to compute $\mathbb{Z}_n^*$, the unit group of the integers modulo $n$?
Fixed Set Property?
A question about Poker (and probability in general)

You have two lengths of rope. If you set fire to the end of either of them, the rope will burn in exactly one hour. They are not the same length or width as each other. They also are not of uniform width (they might, for example, be wider in the middle than at the end), thus burning half of the rope is not necessarily going to take $30$ minutes. By burning the ropes, how do you measure exactly $45$ minutes worth of time?

Note : I don’t know whether a solution even exists at all.

- Proving that an integer is the $n$ th power
- Do expressions like $(-1)^{2/3}$ show up naturally in pure or applied math?
- Multiplication, What is It?
- What is the standard interpretation of order of operations for the basic arithmetic operations?
- Understanding Strategy:Minimum number of weighing to find the faulty bag
- Solving simple congruences by hand

- How to define addition through multiplication?
- Is it possible to practice mental math too often?
- Is $2^k = 2013…$ for some $k$?
- How many triangles
- Fly and Two Trains Riddle
- How to Compare powers without calculating?
- Is there any simple method to calculate $\sqrt x$ without using logarithm
- In the card came “Projective Set”, show that 7 cards do always contain a set.
- Arithmetic progression
- Is it possible to solve the Zebra Puzzle/Einstein's Riddle using pure math?

**HINT** You can burn a rope at both ends.

First burn the first rope from both ends and the second one from first end. After the first rope burns out light the other end of the second rope as well.It will give you 45 minutes.(I know I have told you Swapnanil, but this is for everyone else.)

- An open ball is an open set
- Find volume of crossed cylinders without calculus.
- Is there a real-valued function $f$ such that $f(f(x)) = -x$?
- Is a Sudoku a Cayley table for a group?
- Why is the expression $\underbrace{n\cdot n\cdot \ldots n}_{k \text{ times}}$ bad?
- There are at least three mutually non-isomorphic rings with $4$ elements?
- Suppose every subsequence of X converges to 0. Show that lim(X)=0
- Principal period of $\sin\frac{3x}{4}+\cos\frac{2x}{5}$
- Inductive vs projective limit of sequence of split surjections
- Residues of the product of the gamma and zeta functions.
- Proving and Modeling Logical Consistence
- Tough quadrilogarithm integral
- What's the nth integral of $\frac1{x}$?
- Proof for the curl of a curl of a vector field
- On the spectrum of the sum of two commuting elements in a Banach algebra