PM> Install-Package Spire.Doc

using Spire.Doc;
using Spire.Doc.Documents;
using Spire.Doc.Fields.OMath;

namespace AddMathEquations
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //Create a string array from LaTeX code
            string[] latexMathCode = {
                "x^{2}+\\sqrt{x^{2}+1}=2",
                "\\cos (2\\theta) = \\cos^2 \\theta - \\sin^2 \\theta",
                "k_{n+1} = n^2 + k_n^2 - k_{n-1}",
                "\\frac {\\frac {1}{x}+ \\frac {1}{y}}{y-z}",
                "\\int_0^ \\infty \\mathrm {e}^{-x} \\, \\mathrm {d}x",
                "\\forall x \\in X, \\quad \\exists y \\leq \\epsilon",
                "\\alpha, \\beta, \\gamma, \\Gamma, \\pi, \\Pi, \\phi, \\varphi, \\mu, \\Phi",
                "A_{m,n} = \\begin{pmatrix} a_{1,1} & a_{1,2} & \\cdots & a_{1,n} \\\\ a_{2,1} & a_{2,2} & \\cdots & a_{2,n} \\\\ \\vdots  & \\vdots  & \\ddots & \\vdots  \\\\ a_{m,1} & a_{m,2} & \\cdots & a_{m,n} \\end{pmatrix}",
            };

            //Create a string array from MathML code
            string[] mathMLCode = {
                "<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>a</mi><mo>≠</mo><mn>0</mn></math>",
                "<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>a</mi><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>b</mi><mi>x</mi><mo>+</mo><mi>c</mi><mo>=</mo><mn>0</mn></math>",
                "<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>x</mi><mo>=</mo><mrow><mfrac><mrow><mo>−</mo><mi>b</mi><mo>±</mo><msqrt><msup><mi>b</mi><mn>2</mn></msup><mo>−</mo><mn>4</mn><mi>a</mi><mi>c</mi></msqrt></mrow><mrow><mn>2</mn><mi>a</mi></mrow></mfrac></mrow></math>",
            };

            //Create a Document instance
            Document doc = new Document();

            //Add a section
            Section section = doc.AddSection();

            //Add a paragraph to the section
            Paragraph textPara = section.AddParagraph();
            textPara.AppendText("Creating Equations from LaTeX Code");
            textPara.ApplyStyle(BuiltinStyle.Heading1);
            textPara.Format.HorizontalAlignment = HorizontalAlignment.Center;

            //Iterate through each LaTeX code in the string array
            for (int i = 0; i < latexMathCode.Length; i++)
            {
                //Create a math equation from the LaTeX code
                OfficeMath officeMath = new OfficeMath(doc);
                officeMath.FromLatexMathCode(latexMathCode[i]);
                //Add the math equation to the section
                Paragraph paragraph = section.AddParagraph();                                
                paragraph.Items.Add(officeMath);
                section.AddParagraph();
            }

            section.AddParagraph();

            //Add a paragraph to the section
            textPara = section.AddParagraph();
            textPara.AppendText("Creating Equations from MathML Code");
            textPara.ApplyStyle(BuiltinStyle.Heading1);
            textPara.Format.HorizontalAlignment = HorizontalAlignment.Center;

            //Iterate through each MathML code in the string array
            for (int j = 0; j < mathMLCode.Length; j++)
            {
                //Create a math equation from the MathML code
                OfficeMath officeMath = new OfficeMath(doc);
                officeMath.FromMathMLCode(mathMLCode[j]);
                //Add the math equation to the section
                Paragraph paragraph = section.AddParagraph();
                paragraph.Items.Add(officeMath);               
                section.AddParagraph();
            }

            //Save the result document    
            doc.SaveToFile("AddMathEquations.docx", FileFormat.Docx2013);
            doc.Dispose();
        }
    }
}

Imports Spire.Doc
Imports Spire.Doc.Documents
Imports Spire.Doc.Fields.OMath

Namespace AddMathEquations
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Create a string array from LaTeX code
            Dim latexMathCode = {"x^{2}+\sqrt{x^{2}+1}=2", "\cos (2\theta) = \cos^2 \theta - \sin^2 \theta", "k_{n+1} = n^2 + k_n^2 - k_{n-1}", "\frac {\frac {1}{x}+ \frac {1}{y}}{y-z}", "\int_0^ \infty \mathrm {e}^{-x} \, \mathrm {d}x", "\forall x \in X, \quad \exists y \leq \epsilon", "\alpha, \beta, \gamma, \Gamma, \pi, \Pi, \phi, \varphi, \mu, \Phi", "A_{m,n} = \begin{pmatrix} a_{1,1} & a_{1,2} & \cdots & a_{1,n} \\ a_{2,1} & a_{2,2} & \cdots & a_{2,n} \\ \vdots  & \vdots  & \ddots & \vdots  \\ a_{m,1} & a_{m,2} & \cdots & a_{m,n} \end{pmatrix}"}

            'Create a string array from MathML code
            Dim mathMLCode = {"<math xmlns=""http://www.w3.org/1998/Math/MathML""><mi>a</mi><mo>≠</mo><mn>0</mn></math>", "<math xmlns=""http://www.w3.org/1998/Math/MathML""><mi>a</mi><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>b</mi><mi>x</mi><mo>+</mo><mi>c</mi><mo>=</mo><mn>0</mn></math>", "<math xmlns=""http://www.w3.org/1998/Math/MathML""><mi>x</mi><mo>=</mo><mrow><mfrac><mrow><mo>−</mo><mi>b</mi><mo>±</mo><msqrt><msup><mi>b</mi><mn>2</mn></msup><mo>−</mo><mn>4</mn><mi>a</mi><mi>c</mi></msqrt></mrow><mrow><mn>2</mn><mi>a</mi></mrow></mfrac></mrow></math>"}

            'Create a Document instance
            Dim doc As Document = New Document()

            'Add a section
            Dim section As Section = doc.AddSection()

            'Add a paragraph to the section
            Dim textPara As Paragraph = section.AddParagraph()
            textPara.AppendText("Creating Equations from LaTeX Code")
            textPara.ApplyStyle(BuiltinStyle.Heading1)
            textPara.Format.HorizontalAlignment = HorizontalAlignment.Center

            'Iterate through each LaTeX code in the string array
            For i = 0 To latexMathCode.Length - 1
                'Create a math equation from the LaTeX code
                Dim officeMath As OfficeMath = New OfficeMath(doc)
                officeMath.FromLatexMathCode(latexMathCode(i))
                'Add the math equation to the section
                Dim paragraph As Paragraph = section.AddParagraph()
                paragraph.Items.Add(officeMath)
                section.AddParagraph()
            Next

            section.AddParagraph()

            'Add a paragraph to the section
            textPara = section.AddParagraph()
            textPara.AppendText("Creating Equations from MathML Code")
            textPara.ApplyStyle(BuiltinStyle.Heading1)
            textPara.Format.HorizontalAlignment = HorizontalAlignment.Center

            'Iterate through each MathML code in the string array
            For j = 0 To mathMLCode.Length - 1
                'Create a math equation from the MathML code
                Dim officeMath As OfficeMath = New OfficeMath(doc)
                officeMath.FromMathMLCode(mathMLCode(j))
                'Add the math equation to the section
                Dim paragraph As Paragraph = section.AddParagraph()
                paragraph.Items.Add(officeMath)
                section.AddParagraph()
            Next

            'Save the result document    
            doc.SaveToFile("AddMathEquations.docx", FileFormat.Docx2013)
            doc.Dispose()
        End Sub
    End Class
End Namespace

PM> Install-Package Spire.Doc

using Spire.Doc;

namespace DigitallySignWord
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Document object
            Document doc = new Document();

            //Load a Word file
            doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\sample.docx");

            //Specify the certificate path
            string certificatePath = "C:\\Users\\Administrator\\Desktop\\gary.pfx";

            //Specify the password of the certificate
            string password = "e-iceblue";

            //Digitally sign the document while saving it to a .docx file
            doc.SaveToFile("AddDigitalSignature.docx", FileFormat.Docx2013, certificatePath, password);
        }
    }
}

Imports Spire.Doc
 
Namespace DigitallySignWord
    Class Program
        Shared  Sub Main(ByVal args() As String)
            'Create a Document object
            Document doc  =  New Document()
 
            'Load a Word file
            doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\sample.docx")
 
            'Specify the certificate path
            Dim certificatePath As String =  "C:\\Users\\Administrator\\Desktop\\gary.pfx" 
 
            'Specify the password of the certificate
            Dim password As String =  "e-iceblue" 
 
            'Digitally sign the document while saving it to a .docx file
            doc.SaveToFile("AddDigitalSignature.docx", FileFormat.Docx2013, certificatePath, password)
        End Sub
    End Class
End Namespace