MainWindow.xaml

<Window x:Class="Math.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Math"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <DockPanel LastChildFill="True">
        <StackPanel Orientation="Horizontal" DockPanel.Dock="Top" Margin="8">
            <Button Width="100" Height="25" Command="{Binding StartCommand}" CommandParameter="{Binding Generate}">开始</Button>
            <TextBlock Margin="5 0 0 0" VerticalAlignment="Center">生成</TextBlock>
            <TextBox Text="{Binding Generate}" Margin="5 0 0 0" Width="200" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"></TextBox>
            <TextBlock Margin="5 0 0 0" VerticalAlignment="Center">道</TextBlock>
            <TextBlock Margin="25 0 0 0" VerticalAlignment="Center">只算19以内乘法</TextBlock>
            <CheckBox Margin="5 0 0 0" IsChecked="{Binding Less20}" VerticalAlignment="Center"></CheckBox>
        </StackPanel>
        <StackPanel Orientation="Horizontal" DockPanel.Dock="Bottom" Margin="8">
            <TextBlock FontSize="15" Text="总共："></TextBlock>
            <TextBlock Margin="5 0 0 0" FontSize="15" Text="{Binding Total}"></TextBlock>
            <TextBlock Margin="20 0 0 0" FontSize="15" Text="当前："></TextBlock>
            <TextBlock Margin="5 0 0 0" FontSize="15" Text="{Binding Current}"></TextBlock>
        </StackPanel>
        <StackPanel Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Center">
            <TextBlock Text="{Binding Formula}" FontSize="100"></TextBlock>
            <TextBox Text="{Binding Result}" KeyDown="TextBox_KeyDown" Foreground="{Binding Foreground}" TextChanged="TextBox_TextChanged" Width="400" BorderThickness="0" FontSize="100" HorizontalContentAlignment="Center"></TextBox>
        </StackPanel>
    </DockPanel>
</Window>