dynamically calculate the price in Gridview when the quantity goes up

I have the following gridview . I want the price to be calculated automatically as soon as the user increases or decreases the quantity.

Below is my gridview code:

<asp:GridView ID="grdShoppingCart" runat="server" AutoGenerateColumns="false" class="ui-responsive table-stroke ss-table ui-search-result-table" GridLines="None" OnRowUpdating="test">
                <Columns>
                    <asp:BoundField DataField="item" HeaderText="Item" HeaderStyle-Font-Bold="true" ItemStyle-Width="35%"  />
                    <asp:TemplateField HeaderText="Description" HeaderStyle-Font-Bold="true" ItemStyle-Width="35%"  >
                        <ItemTemplate>
                            <asp:Label ID="lblDesc" runat="server" Text='<%# Eval("child") %>' /><br />
                            &nbsp;Requested By: &nbsp;<asp:Label ID="lblDesc1" runat="server" Text='<%# Eval("RequestedBy") %>' />
                        </ItemTemplate>

                    </asp:TemplateField>
                       <asp:TemplateField HeaderText="Quantity" ItemStyle-Width="10%" >
                        <ItemTemplate>
                                <input type="number" id="txtQuantity" value='<%# Eval("Quantity") %>'   style="text-align:right;" data-mini="true" min="1" max="100" runat="server"/>
                        </ItemTemplate>
                    </asp:TemplateField>
                       <asp:TemplateField HeaderText="Price" ItemStyle-Width="100%" HeaderStyle-HorizontalAlign="Right">
                        <ItemTemplate>
                                <asp:Label  ID="lblPrice" runat="server" Text= '<%# Int32.Parse(Eval("Quantity").ToString()) * 28 %>' />
                        </ItemTemplate>
                      </asp:TemplateField>

                </Columns>

            </asp:GridView>

Answers:

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Method 1

**ASPX**
 <asp:TemplateField HeaderText="Quantity" ItemStyle-Width="10%" >
                        <ItemTemplate>
                            <asp:TextBox ID="txtqty" runat ="server" TextMode="Number" MaxLength="100" Text='<%# Eval("Quantity") %>' OnTextChanged ="txtqty_TextChanged" AutoPostBack ="true"></asp:TextBox>
                                
                        </ItemTemplate>
                    </asp:TemplateField>

Protected Sub txtqty_TextChanged(sender As Object, e As EventArgs)
        Dim textBox As TextBox = CType(sender, TextBox)

        
        Dim qty As String = textBox.Text
        Dim row As GridViewRow = TryCast((TryCast(sender, TextBox)).NamingContainer, GridViewRow)
        Dim lblPrice As Label = CType(row.FindControl("lblPrice"), Label)

        lblPrice.Text = Convert.ToInt32(qty) * 28
    End Sub

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