# Category Archives: GFacts

## How to Install and Configure MongoDB in Ubuntu?

MongoDB is an open-source document oriented NoSQL database which is written in C++. MongoDB is schema-less database system and hence its very easy to add… Read More »

Perl is a general-purpose, high level interpreted and dynamic programming language. It was developed by Larry Wall, in 1987. There is no official Full form… Read More »

## 10 Interesting Facts About Computers

Computers have changed our lives in unimaginable ways. They have made our lives so much easier. Here are 10 scintillating facts about computers: The first… Read More »

The amount of information we are surrounded with is literally exploding every single day and there is an immediate need to organise all these data.… Read More »

## Can C++ reference member be declared without being initialized with declaration?

To many readers, this might sound the same thing, i.e. class_type *var = NULL; *var = &some_work; is same as class_type *var = &some_work; But… Read More »

## Facts and Question related to Style of writing programs in C/C++

Here are some questions related to Style of writing C programs: Question-1: Why i++ executes faster than i + 1 ? Answer-1: The expression i++… Read More »

## Dilworth’s Theorem

Let S be a finite partially ordered set. The size of a maximal antichain equals the size of a minimal chain cover of S. This… Read More »

## Storage of integer and character values in C

Integer and character variables are used so often in the programs, but how these values are actually stored in C are known to few. Below… Read More »

## Vantieghems Theorem for Primality Test

Vantieghems Theorem is a necessary and sufficient condition for a number to be prime. It states that for a natural number n to be prime,… Read More »

## Cauchy’s Mean Value Theorem

Suppose f(x) and g(x) are 2 functions satisfying three conditions: 1) f(x), g(x) are continuous in the closed interval a <= x <= b 2)… Read More »

## Nesbitt’s Inequality

Nesbitt’s inequality is one of the simplest inequalities in mathematics. According to the statement of the inequality, for any 3 given real numbers they satisfy… Read More »

## GFact 23 | (Brocard’s problem)

Brocard’s problem is to find values of m and n such that n!+1 = m2 For example, a pair (4, 5) solves the above equation.… Read More »

## GFact 22 | (2^x + 1 and Prime)

A number of the form 2x + 1 (where x > 0) is prime if and only if x is a power of 2, i.e.,… Read More »

## G-Fact 21 | Collatz Sequence

Starting with any positive integer N, we define the Collatz sequence corresponding to N as the numbers formed by the following operations: N → N/2… Read More »

## G-Fact 20 (Cayley’s formula for Number of Labelled Trees)

Consider below questions. How many spanning trees can be there in a complete graph with n vertices? How many labelled Trees (please note trees, not… Read More »