User learning

24 votes

6 answers

9k views

What is the sum of all positive even divisors of 1000?

asked Sep 12, 2016 at 3:12

11 votes

6 answers

843 views

To find whether $a$ is a prime number

prime-numbers

asked May 27, 2016 at 20:06

11 votes

7 answers

3k views

What is the sum of the $81$ products in the $9 \times 9$ multiplication grid?

arithmetic

asked Jun 11, 2016 at 22:23

8 votes

1 answer

399 views

What is the probability that they have no common prime factor?

probability

asked Jun 15, 2016 at 18:52

8 votes

6 answers

507 views

Find the value of $\frac{a^2}{a^4+a^2+1}$ if $\frac{a}{a^2+a+1}=\frac{1}{6}$

algebra-precalculus

asked May 25, 2016 at 0:07

6 votes

1 answer

18k views

What is the smallest composite number

prime-numbers

asked Jun 3, 2016 at 2:52

6 votes

3 answers

1k views

find the largest number

algebra-precalculus arithmetic

asked May 16, 2016 at 16:40

5 votes

3 answers

546 views

Find the last digit of $3^{1999}$

elementary-number-theory modular-arithmetic chinese-remainder-theorem

asked Jun 18, 2016 at 4:11

5 votes

2 answers

936 views

At least how many students like all the activities?

combinatorics

asked Jun 6, 2016 at 0:53

4 votes

2 answers

463 views

Prove the number of divisors

prime-numbers

asked Sep 5, 2016 at 15:14

3 votes

2 answers

55 views

Find the smallest real value of $x$

factoring

asked Sep 22, 2016 at 17:26

3 votes

1 answer

47 views

Find the other factor

factoring

asked Sep 22, 2016 at 17:57

3 votes

2 answers

1k views

If $x$ and $y$ are positive numbers less than $20$ for which $x+y+xy=76$, what is $x+y$?

algebra-precalculus elementary-number-theory

asked Jun 5, 2016 at 2:37

3 votes

3 answers

636 views

What is the sum of the prime factors of $2^{16}-1$?

factoring prime-factorization

asked Jun 5, 2016 at 3:40

3 votes

2 answers

400 views

How many ways can all six numbers in the set $\{4, 3, 2, 12, 1, 6\}$ be ordered

order-theory

asked Jun 11, 2016 at 17:26

3 votes

1 answer

2k views

How many positive two-digit integers have exactly 8 positive factors?

factoring

asked Jun 12, 2016 at 2:26

3 votes

2 answers

1k views

how many distinct values does it have?

combinatorics

asked May 22, 2016 at 21:25

3 votes

3 answers

115 views

A question about $ax = b$

inequality

asked May 27, 2016 at 2:18

2 votes

2 answers

38 views

given an equation, find A and B

partial-fractions

asked Jun 5, 2016 at 2:21

2 votes

2 answers

831 views

How many three-digit primes less than 200 have two digits the same?

elementary-number-theory prime-numbers

asked Jun 3, 2016 at 3:16

2 votes

4 answers

751 views

What is the smallest possible value of $n$?

algebra-precalculus

asked Jun 11, 2016 at 17:15

2 votes

2 answers

299 views

What is the largest prime factor of $55^{100}+55^{101}+55^{102}$

factoring

asked Sep 22, 2016 at 18:04

2 votes

4 answers

1k views

For how many positive integers $a$ is $a^4−3a^2+9$ a prime number?

elementary-number-theory prime-numbers

asked Sep 19, 2016 at 18:15

2 votes

2 answers

547 views

The sum of the cubes of two different prime numbers is 5256.

elementary-number-theory prime-numbers diophantine-equations

asked Sep 19, 2016 at 18:34

2 votes

4 answers

224 views

What is the value of $x$ in $222^x−111^x∗7=111^x$?

factoring

asked Sep 22, 2016 at 16:34

2 votes

2 answers

137 views

Use the $\epsilon-\delta$ definition of limit to prove that $\lim\limits_{x\to2}x^2 = 4$

calculus

asked Jun 10, 2018 at 13:32

2 votes

2 answers

360 views

how many of the resulting number are divisible by 11 but not by 5?

divisibility

asked Oct 11, 2016 at 0:17

1 vote

6 answers

557 views

Find the real solutions of the equations:$x+y=2$, $xy-z^2=1$

algebra-precalculus

asked Oct 4, 2016 at 15:35

1 vote

1 answer

76 views

Seven-element lists of integers with conditions on means

statistics means

asked Oct 10, 2016 at 12:53

1 vote

1 answer

595 views

What is the volume of this octahedron?

volume

asked Oct 10, 2016 at 23:22

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74 Questions

What is the sum of all positive even divisors of 1000?

To find whether $a$ is a prime number

What is the sum of the $81$ products in the $9 \times 9$ multiplication grid?

What is the probability that they have no common prime factor?

Find the value of $\frac{a^2}{a^4+a^2+1}$ if $\frac{a}{a^2+a+1}=\frac{1}{6}$

What is the smallest composite number

find the largest number

Find the last digit of $3^{1999}$

At least how many students like all the activities?

Prove the number of divisors

Find the smallest real value of $x$

Find the other factor

If $x$ and $y$ are positive numbers less than $20$ for which $x+y+xy=76$, what is $x+y$?

What is the sum of the prime factors of $2^{16}-1$?

How many ways can all six numbers in the set $\{4, 3, 2, 12, 1, 6\}$ be ordered

How many positive two-digit integers have exactly 8 positive factors?

how many distinct values does it have?

A question about $ax = b$

given an equation, find A and B

How many three-digit primes less than 200 have two digits the same?

What is the smallest possible value of $n$?

What is the largest prime factor of $55^{100}+55^{101}+55^{102}$

For how many positive integers $a$ is $a^4−3a^2+9$ a prime number?

The sum of the cubes of two different prime numbers is 5256.

What is the value of $x$ in $222^x−111^x∗7=111^x$?

Use the $\epsilon-\delta$ definition of limit to prove that $\lim\limits_{x\to2}x^2 = 4$

how many of the resulting number are divisible by 11 but not by 5?

Find the real solutions of the equations:$x+y=2$, $xy-z^2=1$

Seven-element lists of integers with conditions on means

What is the volume of this octahedron?