a book store gave 30% discount to every 20th and 21st custmer to enter, AND A FREE BOOK TO EVERY 100TH CUSTMER.
the first custmer to recive both a book and discount is what number?
The 100th customer
To find the number of the first customer who received both a discount and a free book, we need to determine the lowest common multiple (LCM) of 20 and 100.
First, let's break down the conditions:
- Every 20th customer receives a 30% discount.
- Every 21st customer receives a 30% discount.
- Every 100th customer receives a free book.
To find the LCM of 20 and 100, we list the multiples of each number:
Multiples of 20: 20, 40, 60, 80, 100, 120, 140, 160, 180, 200...
Multiples of 100: 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000...
By examining the multiples, we can see that the LCM of 20 and 100 is 100. The customer number associated with the LCM is the first customer to receive both a discount and a free book, which in this case is 100.
Thus, the answer is that the first customer to receive both a book and a discount is customer number 100.