Math-Mard Trick

Before the arrival of the participant, place cards 1 (Ace), 2, 4, 5, 7,  8 on the table.
You may need a calculator.

Ask the participant to choose any card.
In the video we chose # 4.
Follow these instructions:
Multiply the number by 9.
Multiply the answer by 111.
Multiply the answer by 1001. 
Divide the answer by 7. 

Question :
Will each card match a different digit of your answer?

Shuffle the cards. Turn them over one at a time. Find out.

PS: Notice the card sorting dyslexia..:-)