static class ExtensionMethods {
public static decimal Double( this decimal d ) {
	return d + d;
}
public static decimal Triple( this decimal d ) {
	return d * 3;
}
public static decimal Increase( this decimal d ) {
	return d + 1;
}
public static decimal Decrease( this decimal d ) {
	return d - 1;
}
public static decimal Half( this decimal d ) {
	return d / 2;
}
// . . .
}
