the + noun+ number

[Saneta]

http://www.english-test.net/toeic/listening/how_often_does_the_number_4_train_run.html

How often does the number 4 train run?
shoudn't it be:
How often does number 4 train run?
because we don't use 'the' before 'noun + number'= 'number 4'?

thanks a lot!

[Beeesneees]

The noun is 'train'. 'Number 4' is adjectival - it describes which train.

How often does the train run? How often does the number 4 train run?
How fast does the car go? How fast does the red car go?
How quickly can the woman walk? How quickly can the elderly woman walk?
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Cheers m' dears!