User Quixotic - Mathematics Stack Exchange

bio	website
	location
	age
visits	member for	2 years, 9 months
	seen	48 mins ago
stats	profile views	2,332

	8,130 reputation	bio	website		visits	member for	2 years, 9 months
11865 badges		location			seen	48 mins ago

8

27

votes

4

answers

368

views

How does the divisibility graphs work?

jun 8 at 16:40 MJD 22.1k

8

25

votes

5

answers

4

kviews

Checking if a number is a Fibonacci or not?

number-theory fibonacci-numbers

oct 14 at 3:27 clementi 64

2

22

votes

3

answers

427

views

Find the number of pairs of positive integers $(a, b)$ such that $a!+b! = a^b$

combinatorics number-theory contest-math

feb 7 '12 at 23:29 user474632 372

9

21

votes

6

answers

1

kviews

Proving : $ \bigl(1+\frac{1}{n+1}\bigr)^{n+1} \gt (1+\frac{1}{n})^{n} $

algebra-precalculus inequality

oct 21 at 14:18 robjohn♦ 63.3k

10

20

votes

2

answers

1

kviews

A pencil approach to find $\sum \limits_{i=1}^{69} \sqrt{\left( 1+\frac{1}{i^2}+\frac{1}{(i+1)^2}\right)}$

algebra-precalculus

oct 21 '11 at 23:41 Mike Spivey 26.1k

5

16

votes

6

answers

642

views

Which is the easiest way to evaluate $\int \limits_{0}^{\pi/2} (\sqrt{\tan x} +\sqrt{\cot x})$?

calculus integral definite-integral

jan 22 '12 at 8:44 Ishaan Singh 412

2

14

votes

3

answers

734

views

A “fast” way for computing $ \prod \limits_{i=1}^{45}(1+\tan i^\circ) $?

trigonometry products

feb 15 at 6:37 lab bhattacharjee 32.7k

4

13

votes

1

answer

291

views

How many $N$ of the form $2^n$ are there such that no digit is a power of $2$?

combinatorics number-theory contest-math problem-solving

feb 3 '12 at 8:08 Community♦ 1

4

13

votes

2

answers

1

kviews

Significance of $\displaystyle\sqrt[n]{a^n} $?

algebra-precalculus faq

jul 24 '11 at 5:18 Did 107k

6

12

votes

4

answers

395

views

How to prove $\sum\limits_{r=0}^n \frac{(-1)^r}{r+1}\binom{n}{r} = \frac1{n+1}$?

algebra-precalculus binomial-coefficients

mar 16 at 2:22 Tea ryur Kwon 1

6

11

votes

5

answers

4

kviews

Drawing heart in mathematica

geometry plane-curves mathematica

jun 1 at 17:54 Ｊ. M. 39.9k

3

11

votes

1

answer

224

views

If the product of $x$ positive integers is $n!$ What is the smallest possible value their sum can have?

algebra-precalculus elementary-number-theory

oct 20 '11 at 0:54 Ｊ. M. 39.9k

9

votes

2

answers

270

views

Doubt in finding number of non-prime factors of an integer

elementary-number-theory prime-numbers

apr 25 at 11:29 user74313 1

1

9

votes

4

answers

432

views

Which is the fastest way to find the remainder when $2^{400}$ is divided by $400$?

elementary-number-theory

jan 21 '12 at 19:52 Community♦ 1

8

votes

3

answers

310

views

How are the integral parts of $(9 + 4\sqrt{5})^n$ and $(9 − 4\sqrt{5})^n$ related to the parity of $n$?

abstract-algebra elementary-number-theory

dec 25 '11 at 22:51 Community♦ 1

1

8

votes

4

answers

200

views

How could we manually approximate $\sum_{i=1}^{50} i! = 3.1035 \times 10^{64}$?

sequences-and-series approximation

nov 22 '11 at 18:15 Martin Sleziak 20.8k

4

8

votes

0

answers

331

views

Is it possible to find the digit sum of $n!$ ($n \in \mathbb{N} \text{ and } n \le100$) without actually computing the factorial?

elementary-number-theory

nov 7 '11 at 10:11 Quixotic 8,130

8

votes

2

answers

1

kviews

Understanding a famous riddle

algebra-precalculus puzzle

jun 1 '11 at 21:49 duncanm 93

1

8

votes

5

answers

3

kviews

Is the void set (∅) a proper subset of every set?

terminology elementary-set-theory

may 6 '11 at 4:26 Irfan Hassan 11

8

votes

4

answers

259

views

An elementary doubt on Inequalities

algebra-precalculus

mar 8 '11 at 9:24 Isaac 21.2k

4

7

votes

6

answers

401

views

Is it wrong to say $ \sqrt{x} \times \sqrt{x} =\pm x,\forall x \in \mathbb{R}$?

algebra-precalculus fake-proofs

jan 29 at 11:34 Emil Lundberg 101

5

7

votes

1

answer

2

kviews

Last non Zero digit of a Factorial

number-theory elementary-number-theory factorial

jan 22 at 5:37 dinoboy 1,779

1

7

votes

5

answers

231

views

For a polynomial $P$ for which $P(x+5) - P(x) = 2 ,\forall x$. What is the least possible value of $P(4) - P(2)$?

algebra-precalculus polynomials

feb 11 '12 at 18:45 Community♦ 1

1

7

votes

4

answers

329

views

A “fast” way to manually compute $3^{41}+7^{41} \pmod{13}$

abstract-algebra elementary-number-theory modular-arithmetic

dec 14 '11 at 4:21 Srivatsan 15.7k

1

7

votes

3

answers

371

views

How could we find the largest number in the sequence $ \sqrt{50},2\sqrt{49},3\sqrt{48},\cdots 49\sqrt{2},50$?

sequences-and-series algebra-precalculus elementary-number-theory

nov 8 '11 at 14:38 Tapu 2,756

7

votes

6

answers

217

views

Finding the minimum number of students

combinatorics

sep 2 '11 at 4:42 Ross Millikan 87k

7

votes

4

answers

330

views

How to compute that the unit digit of $\frac{(7^{6002} − 1)}{2}$?

number-theory elementary-number-theory

aug 27 '11 at 18:32 Community♦ 1

5

6

votes

4

answers

518

views

How many rationals of the form $\large \frac{2^n+1}{n^2}$ are integers?

number-theory contest-math problem-solving

4h ago Arjang 2,501

1

6

votes

3

answers

284

views

Optimal algorithm for finding the odd spheres

algorithms

mar 20 at 20:18 Thomas Pornin 141

3

6

votes

4

answers

603

views

Confusion over probability problems

probability combinatorics dice

mar 6 at 19:41 azimut 5,783

Quixotic

344 Questions