I'm working on a program that calculates the day of the week for dates in history or the future. I have the calculation part correctly but there are 4 errors left that I do not know how to fix. Any help will be greatly appreciated!

Thanks

import java.util.Scanner;

public class DayOfWeek
{
	public static int Month(String Month)
	{
		int Monthnum;
		if(Month.equals("January") || Month.equals("October"))
		{
			Monthnum = 3;
		}
		if(Month.equals("February") || Month.equals("March") || Month.equals("November"))
		{
			Monthnum = 6;
		}
		if(Month.equals("April") || Month.equals("July"))
		{
			Monthnum = 2;
		}
		if(Month.equals("May"))
		{
			Monthnum = 4;
		}
		if(Month.equals("June"))
		{
			Monthnum = 0;
		}
		if(Month.equals("August"))
		{
			Monthnum = 5;
		}
		if(Month.equals("September") || Month.equals("December"))
		{
			Monthnum = 1;
		}
		return Monthnum;
	}

	public static int Century (int Century)
	{
		int Centurynum;
		if(Century > 1752 && Century < 1799)
		{
			Centurynum = 2;
		}
		if(Century > 1800 && Century < 1899)
		{
			Centurynum = 0;
		}
		if(Century > 1900 && Century < 1999)
		{
			Centurynum = 5;
		}
		if(Century > 2000 && Century < 2099)
		{
			Centurynum = 4;
		}
		if(Century > 2100 && Century < 2200)
		{
			Centurynum = 2;
		}
		return Centurynum;
	}

	public static int DOWnum (int DOWnum)
	{
		String DOW;
		if(DOWnum== 1)
		{
			DOW = ("Sunday");
		}
		if(DOWnum== 2)
		{
			DOW = ("Monday");
		}
		if(DOWnum== 3)
		{
			DOW = ("Tuesday");
		}
		if(DOWnum== 4)
		{
			DOW = ("Wednesday");
		}
		if(DOWnum== 5)
		{
			DOW = ("Thursday");
		}
		if(DOWnum== 6)
		{
			DOW = ("Friday");
		}
		if(DOWnum = 0)
		{
			DOW = ("Saturday");
		}
		return DOW;
	}

	public static void main (String [] args)
	{
		Scanner input=new Scanner(System.in);
		System.out.println("This Program will find what day of the week any date was prier to September 14th, 1752");
		System.out.println(" ");
		int Century, Centurynum, Monthnum, date, Century1, dividedfour, total, DOWnum;
		System.out.print("Please enter the month(Full name ex: January): ");
		String Month = input.nextLine();
		System.out.print("Please enter the day of the month: ");
		date = input.nextInt();
		System.out.print("Please enter the year(ex: 1900): ");
		Century = input.nextInt();
		Monthnum = Month(Month);
		Centurynum = Century(Century);
		Century1 = (Century%1000)%100;
		dividedfour = Math.floor(Century1/4);
		total = Century1+dividedfour+Centurynum+Monthnum+date;
		DOWnum = total%7;
		String DOW = DOWnum(DOWnum);
		System.out.print(DOW);
	}
}

You are getting simple compilation errors.
In

public static int DOWnum (int DOWnum)

you are trying to return a String. So change the return type of the method to String.

Also in

if(DOWnum = 0)
{
DOW = ("Saturday");
}

you are assigning '0' to DOWnum. Change it to

if(DOWnum == 0)
{
DOW = ("Saturday");
}

Also

Math.floor(Century1/4);

returns a double. So when assigning double to int compiler complains about the data truncation. So do a explicit cast
dividedfour = (int)Math.floor(Century1/4);

And finally, initialize the variables that you define inside methods to its default value.

Didn't initialize Monthnum:

int Monthnum = 0;

Didn't initialize Centurynum:

int Centurynum = 0;

Forgot your ==, an int can't be a boolean:

if(DOWnum == 0)
		{
			DOW = ("Saturday");
		}

You're trying to return a string, but your method is declared as type int, also must initialize DOW:

public static String DOWnum (int DOWnum)
	{
		String DOW = null;

dividedfour was declared as an int, yet it was equaled to a double, just add a cast to int:

dividedfour = (int) Math.floor(Century1/4);

Also, assuming this should be after September 14, 1752:

System.out.println("This Program will find what day of the week any date was after September 14th, 1752");
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