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How do I add the last typed number to a total?

I'm new to learning C# and I was wondering how to keep adding numbers I type to a total number. Right now instead of adding up all the numbers I typed in before typing 0, it just takes the last typed in number... The number count does go up however, which is why I'm pretty confused.
For example:
Enter number: 2
Enter number: 6
Enter number: 4
Enter number: 7
Enter number: 0
There are 4 positive numbers (Works like I intended)
The total amount is 7 (Is supposed to be 2+6+4+7 = 21)
Console.Write("Enter number: ");
string numberInput = Console.ReadLine();
double number = double.Parse(numberInput);
int count = 0;
double begin = 0;
double total = 0;
while (number != 0)
{
if (number >= 0)
{
count++;
total = begin + number;
}
Console.Write("Enter number: ");
number = double.Parse(Console.ReadLine());
}
double average = total / count;
Console.WriteLine("There are {0} positive numbers", count);
Console.WriteLine("The total amount is {0}", total);
Console.WriteLine("Your average is: {0}", average);
Console.ReadKey();

I figured it out already, had to change this:
total = begin + number;
to
total = total + number;

You don't need to use begin variable as you can sum input values like below:
total += number; // This is the same with 'total = total + number;'
As a suggestion, you can improve your code using do while loop like below:
int count = 0;
double total = 0;
double number;
do
{
Console.Write("Enter number: ");
number = double.Parse(Console.ReadLine());
if (number > 0)
{
count++;
total += number;
}
} while (number != 0);
double average = total / count;
Console.WriteLine("There are {0} positive numbers", count);
Console.WriteLine("The total amount is {0}", total);
Console.WriteLine("Your average is: {0}", average);
Console.ReadKey();

How do I sum up every 5th number instead of all numbers?

I need some help with the for-loop. I'm trying to sum up every fifth number that I type in, instead it sums them all up. What do I have to change?
int count = 0;
double total = 0;
Console.Write("Enter your number: ");
int input = int.Parse(Console.ReadLine());
while (input != 0)
{
count++;
for (count = 0; count <= 0; count += 5)
{
total = total + input;
}
Console.Write("Enter your number: ");
input = int.Parse(Console.ReadLine());
}
Console.WriteLine("The sum of every +5 numbers is: {0}", total);
Console.ReadKey();

Assuming that you enter a list of numbers, and the 1st number and every five afterwards is added (so 1st, 6th, 11th, etc.):
int count = 0;
double total = 0;
Console.Write("Enter your number: ");
int input = int.Parse(Console.ReadLine());
while (input != 0)
{
count++;
if (count % 5 == 1)
total = total + input;
Console.Write("Enter your number: ");
input = int.Parse(Console.ReadLine());
}
Console.WriteLine("The sum of every +5 numbers is: {0}", total);
Console.ReadKey();
This works by using the modulo operator (%). The modulo operator returns the remainder of a division operation involving the number you specify.
In the code if (count % 5 == 1), the question is:
Is the remainder of count divided by 5 equal to 1?
If so, it adds the number. If not, it is skipped
The reason the remainder is one is because we want results 1, 6, 11, etc:
1 / 5 = remainder 1
6 / 5 = remainder 1
11 / 5 = remainder 1
If you change the modulo value to 0 it will return the results at position 5, 10, 15, etc.

You could just store the numbers in a list and calculate it at the end:
var numbers = new List<int>();
Console.Write("Enter your number: ");
var input = int.Parse(Console.ReadLine());
while (input != 0)
{
numbers.Add(input);
input = int.Parse(Console.ReadLine());
}
var total = numbers.Where((x, i) => (i + 1) % 5 == 0).Sum(); // i + 1 since indexes are 0-based.
Console.WriteLine("The sum of every +5 numbers is: {0}", total);

You can try this:
double total = 0;
int passover = 4;
int input = 0;
do
{
passover++;
Console.Write("Enter your number: ");
int.TryParse(Console.ReadLine(), out input);
if ( passover != 5 ) continue;
passover = 1;
total = total + input;
}
while ( input != 0 );
Console.WriteLine("The sum of every fifth numbers is: {0}", total);
Console.ReadKey();

I think the best way is to recover all the values ​​before making the sum, this code works:
double total = 0;
int input = -1;
List<int> allInput = new List<int>();
while (input != 0)
{
Console.Write("Enter your number: ");
input = int.Parse(Console.ReadLine());
allInput.Add(input);
}
for (int i = 0; i < allInput.Count()-1; i += 5)
{
total = total + allInput[i];
}
Console.WriteLine("The sum of every +5 numbers is: {0}", total);
Console.ReadKey();

Your sample would go forever, because there is no break point in your loop. You should always put a break point in your loop, otherwise it'll loop indefinitely.
Here is what you need :
int total = 0;
int count = 0;
Console.Write("Enter your number: ");
while (true)
{
int input = 0;
bool isNumber = int.TryParse(Console.ReadLine(), out input);
if (isNumber)
{
count++;
if (count % 5 == 0)
total += input;
}
else
{
break;
}
Console.Write("Add another number or press enter to get the sum : ");
}
Console.WriteLine("The sum of every +5 numbers is: {0}", total);
Console.ReadKey();
So, you'll need first to put the user input inside a loop, and keep asking the user for adding another number until hits the condition where you close this loop. In the example, I decided to break the loop if the user typed anything not a number. but I told the user to press enter to get the some, to end the loop. For you, you'll need to translate that to your application breakpoint, how would you want the user to get the sum ?. Then, change the condition to your logic, so it breaks the loop and gets the sum.
another point is that int.TryParse. When you want to convert strings to numbers (int, long, decimal ..etc). You should always use `TryParse, this will verify the number, if the conversion failed, it'll return false. This way you can maintain the conversion and do something about it.

C# writing a program that input of 2 numbers (a and b),gives an output of the sum of squares in between

I`m quite new to the whole programming world.
And i started studying C#
i got the following exersice to do:
Write a program that upon the input of 2 numbers (a and b), u receive
an output of the sum of squares in between.
I.e. - The program receives a and b where b > a and calculates a^2
+ (a+1)^2 + (a+2)^2 + ... + (b-1)^2 + b^2.
E.g. - If a = 3 and b = 6, the output would be 86, since 3^2 +
4^2 + 5^2 + 6^2 = 9 + 16 + 25 + 36 = 86
But i don't have any idea where do i even begin.
I`m guessing i need some sort of loop within a loop maybe?

You need to use for loop for this. Please see below, if that helps-
int i, j, k;
int value=0;
Console.WriteLine("Enter the fist number ");
i = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Enter the second number ");
j = Convert.ToInt32(Console.ReadLine());
if (i > j)
{
Console.WriteLine("Second number should be greater then First");
Console.ReadLine();
Environment.Exit(0);
}
for (k = i; k <= j; k++)
{
value += k * k;
}
Console.WriteLine(value);
Console.ReadLine();

Perhaps a method that takes in two integers and returns a double is a good place to start (returning a double allows you to specify a wider range of numbers without getting inaccurate results):
public static double GetSumOfSquaresBetween(int first, int second)
{
}
Then you could implement the body by creating a loop that goes from the lowest number to the highest number, adding the square of the current number to a result, and then returning that result at the end.
Here's a Linq example that would most likely not be acceptable for this assignment but gives you the idea:
public static double GetSumOfSquaresBetween(int first, int second)
{
return Enumerable
.Range(Math.Min(first, second), Math.Abs(first - second) + 1)
.Select(number => Math.Pow(number, 2))
.Sum();
}

Try this
int a, b, sum = 0;
Console.WriteLine("Enter the fist number ");
a = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Enter the second number ");
b = Convert.ToInt32(Console.ReadLine());
if (a<b){
for (int x = a+1; x < b; x++)
{
sum += x * x;
}
Console.WriteLine(sum);
}
else{
Console.WriteLine("Wrong input!");
}
Console.ReadLine();
}
}

A for loop should do it.
double nTotal = 0;
for (int a = 3; a <= 6; a++)
{
nTotal += Math.Pow(a, 2);
}

Find if a number is within Fibonacci range

I have printed some Fibonacci numbers. Now I want to see if a number / which I enter / is within that range and if it is, to show it's position.
This is what I have so far:
using System;
namespace SomeFibonacciPrimes
{
class SomeFibonacciPrimes
{
static void Main()
{
int first = 0;
int second = 1;
int third = 1;
for (int i = 0; i < 50; i++)
{
third = second;
second = first + second;
first = third;
Console.WriteLine(second);
}
Console.WriteLine("Enter a number to find if it's in Fibonacci range:");
int number = int.Parse(Console.ReadLine());
if (number == second)
{
Console.WriteLine("Your number is within the Fibonacci range.");
}
else
{
Console.WriteLine("Your number is NOT within the Fibonacci range");
}
}
}
}
I can't understand why the If statement prints the else result if I enter a number that I SEE in the range?!
I think that after I manage to make the If statement to work, the position is the "i" in the for statement?

I suggest you to use either an array of integer or List of integer to solve this: as like the following:
int first = 0;
int second = 1;
int third = 1;
List<int> fibnoList= new List<int>();
for (int i = 0; i < 50; i++)
{
fibnoList.Add(second);
Console.WriteLine(second); //To print the series
third = second;
second = first + second;
first = third;
}
Console.WriteLine("Enter a number to find if it's in Fibonacci range:");
int number = int.Parse(Console.ReadLine());
if (fibnoList.Contains(number))
{
Console.WriteLine("Your number is within the Fibonacci range.");
}
else
{
Console.WriteLine("Your number is NOT within the Fibonacci range");
}

Aside from using looping, maybe you can consider this
using System;
namespace SomeFibonacciPrimes
{
class SomeFibonacciPrimes
{
static void Main()
{
Console.WriteLine("Enter a number to find if it's in Fibonacci range:");
int number = int.Parse(Console.ReadLine());
if (IsFibonacci(number))
{
Console.WriteLine("Your number is within the Fibonacci range.");
}
else
{
Console.WriteLine("Your number is NOT within the Fibonacci range");
}
}
static bool IsFibonacci(int number)
{
//Uses a closed form solution for the fibonacci number calculation.
//http://en.wikipedia.org/wiki/Fibonacci_number#Closed-form_expression
double fi = (1 + Math.Sqrt(5)) / 2.0; //Golden ratio
int n = (int) Math.Floor(Math.Log(number * Math.Sqrt(5) + 0.5, fi)); //Find's the index (n) of the given number in the fibonacci sequence
int actualFibonacciNumber = (int)Math.Floor(Math.Pow(fi, n) / Math.Sqrt(5) + 0.5); //Finds the actual number corresponding to given index (n)
return actualFibonacciNumber == number;
}
}
}

C# - displaying the max, min, and average

I am new to C#. I have been working on this program and researching but am not getting anywhere. The goal is to have the user enter numbers (how many is up to the user). when they enter a 0, it will stop the program and display the minimum number entered, the maximum number entered, and the average of all numbers entered. I am not getting any errors and I am getting. If someone can please point me in the right direction.
The WriteLines are returning:
Lowest number is 0
Highest number is 0
Average is: 0
Count: 5
Here is my code:
int LOWEST =0;
int HIGHEST=0;
const int STOP = 0;
double average = 0;
int input;
int count = 0;
Console.WriteLine("Enter a number. You can end the program at anytime by entering 0");
input = Convert.ToInt32(Console.ReadLine());
while (input != STOP)
{
for (int i=0; input != STOP; i++)
{
Console.WriteLine("Enter a number. You can end the program at anytime by entering 0");
input = Convert.ToInt32(Console.ReadLine());
count++;
var Out = new int[] { input };
LOWEST = Out.Min();
HIGHEST = Out.Max();
average = Out.Average();
if ((input > LOWEST) || (input < HIGHEST))
{
LOWEST = Out.Min();
}
if (input > HIGHEST)
{
HIGHEST = Out.Max();
}
}
}
Console.WriteLine("Lowest number is {0}", LOWEST);
Console.WriteLine("Highest number is {0}", HIGHEST);
Console.WriteLine("Average is {0}", average);
Console.WriteLine("Count: {0}", count);
Console.ReadLine();

On each run you are constructing a new array of integers:
var Out = new int[] { input };
After this line, Out contains one item: the last input. Calling Min, Max and Average on it will return the last value. Which is zero if you ended the program.
instead of creating a new array each time, you want to create a List<int> at the beginning of your program and then add each input to it. You can then use the whole list of values to calculate Min, Max and Average.
Eventually you can change your code into something like this:
const int STOP = 0;
int input = -1;
List<int> Out = new List<int>();
while (input != STOP)
{
Console.WriteLine("Enter a number. You can end the program at anytime by entering 0");
input = Convert.ToInt32(Console.ReadLine());
if (input == STOP) break;
Out.Add(input);
}
Console.WriteLine("Lowest number is {0}", Out.Min());
Console.WriteLine("Highest number is {0}", Out.Max());
Console.WriteLine("Average is {0}", Out.Average());
Console.WriteLine("Count: {0}", Out.Count);
Console.ReadLine();

List<int> numbers = new List<int>();
numbers.Add(10);
numbers.Add(30);
numbers.Add(20);
numbers.Add(0);
numbers.Max();
numbers.Min();
numbers.Average();
returns 30, 0 and 15.

Before your loop, you should probably make Out an extensible data structure analogous to an array, the List.
List<int> Out = new List<int>();
then each loop, you can
Out.Add(input);
Since this sounds like an exercise for the reader, you can then traverse your list and compute the average from all data values.
Alternately, before the loop, you could declare
int n = 0;
int total = 0;
and each loop, do
n += 1;
total += input;
From these, you should be easily able to compute the average.