res/layout/numpad.xml

<?xml version="1.0" encoding="utf-8"?>

<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TableRow
        android:layout_width="match_parent"
        android:layout_height="0px"
        android:layout_weight="1">
        <Button android:id="@+id/numButton1"/>
        <Button android:id="@+id/numButton2"/>
        <Button android:id="@+id/numButton3"/>
    </TableRow>
    <TableRow
        android:layout_width="match_parent"
        android:layout_height="0px"
        android:layout_weight="1">
        <Button android:id="@+id/numButton4"/>
        <Button android:id="@+id/numButton5"/>
        <Button android:id="@+id/numButton6"/>
    </TableRow>
    <TableRow
        android:layout_width="match_parent"
        android:layout_height="0px"
        android:layout_weight="1">
        <Button android:id="@+id/numButton7"/>
        <Button android:id="@+id/numButton8"/>
        <Button android:id="@+id/numButton9"/>
    </TableRow>
    <TableRow
        android:layout_width="match_parent"
        android:layout_height="0px"
        android:layout_weight="1">
        <Button android:id="@+id/numButtonStar"/>
        <Button android:id="@+id/numButton0"/>
        <Button android:id="@+id/numButtonSharp"/>
    </TableRow>
</merge>