public static void Main()
{
decimal change = 0;
decimal baseAmount = 0;
while (true)
{
Console.WriteLine("\nPercent Change");
Console.WriteLine("1. Enter change and base amount");
Console.WriteLine("2. Enter new amount and old amount");
Console.WriteLine("3. Enter percentage of change");
Console.WriteLine("4. Quit");
var option = RequireValidDecimal("\nOption: ");
if (option < 1 || option > 4)
{
continue;
}
if (option == 4)
{
Environment.Exit(0);
}
if (option == 1)
{
change = RequireValidDecimal("Enter amount of change: ");
baseAmount = RequireValidDecimal("Enter base amount: ");
Console.WriteLine();
var percentChange = PercentChange(change, baseAmount);
OnlyMathLib.ColorWriteLine($"{baseAmount + change} is an increase of {percentChange * 100:N2}% from {baseAmount}");
OnlyMathLib.ColorWriteLine($"{baseAmount - change} is a decrease of {percentChange * 100:N2}% from {baseAmount}");
}
if (option == 2)
{
var newAmount = RequireValidDecimal("Enter new amount: ");
baseAmount = RequireValidDecimal("Enter old amount: ");
change = Math.Abs(newAmount - baseAmount);
var message = newAmount > baseAmount ? "increase" : "decrease";
Console.WriteLine();
var percentChange = PercentChange(change, baseAmount);
OnlyMathLib.ColorWriteLine($"{newAmount} is an {message} of {percentChange * 100:N2}% from {baseAmount}");
}
if (option == 3)
{
baseAmount = RequireValidDecimal("Enter base amount: ");
var percentChange = RequireValidDecimal("Enter percent change: ");
change = percentChange * baseAmount / 100;
Console.WriteLine();
OnlyMathLib.ColorWriteLine($"{change + baseAmount} is an increase of {percentChange}%");
OnlyMathLib.ColorWriteLine($"{baseAmount - change} is a decrease of {percentChange}%");
}
}
}
private static void CalculateSimpleInterest()
{
Console.WriteLine();
var principal = OnlyMathLib.RequireValidDecimal("Principal Amount: ");
var rate = OnlyMathLib.RequireValidDecimal("Interest rate: ");
var years = OnlyMathLib.RequireValidDecimal("Years: ");
var interest = SimpleInterest(principal, rate / 100, years);
Console.WriteLine();
OnlyMathLib.ColorWriteLine($"Interest: {interest:N2} Principal + Interest: {interest + principal:N2}");
}
private static void CalculateCompoundInterest()
{
Console.WriteLine();
var principal = OnlyMathLib.RequireValidDecimal("Principal Amount: ");
var rate = OnlyMathLib.RequireValidDecimal("Interest rate: ");
var years = OnlyMathLib.RequireValidDecimal("Years: ");
var frequency = OnlyMathLib.RequireValidDecimal("Times compounded per year: ");
var interest = CompoundInterest(principal, rate / 100, frequency, years);
Console.WriteLine();
OnlyMathLib.ColorWriteLine($"Interest: {interest:N2} Principal + Interest: {interest + principal:N2}");
}