!start <number>;
<number>: [[<less_than_1000>] thousand] [<less_than_1000>];
<less_than_1000>: [<less_than_10> hundred] [<less_than_100>];
<less_than_100>: [and] (ten | eleven | twelve | thirteen | fourteen | fifteen | sixteen | seventeen| eighteen | nineteen | [<decimal>] [<less_than_10>]);
<decimal>: twenty | thirty | fourth | fifty | sixty | seventy | eighty | ninety ;
<less_than_10>:  [and] (zero | one | two |  three | four | five | six | seven | eight | nine);