john wants to send a letter to peter who lives on tesla street. John doesn’t remember the house number

Question:- john wants to send a letter to peter who lives on tesla street. John doesn’t remember the house number. However, he knows that it has 4 digits, it is a multiple of 5 and 7 and that the last digit is 0. What is the minimum number of letters that John has to send to be sure that Peter receives his letter?

Answer:- John wants to write a letter for his friend Peter, who resides in Tesla Street. Unfortunately John does not remember the house number on Tesla Street. However, he does recall a few key details about the house number: 1 a) it is four digits long; b) It can be divided by both 5 and 7, c) the final digit stands at zero.

With these clues, John can significantly reduce the possibilities. Since the number should have 4 digits and finish with zero, it falls into the category of thousands between 1000 and USUS999 Next, the divisibility rules reduce most of these numbers from this set. To be divisible by both 5 and 7, a number must end in as stated but also the sum of its digits must scale with multiples of five and seven.

Given these criteria, there are only 3 possible 4-digit house numbers that Peter’s home could be: 3570, 4900, or 7000. To ensure that Peter gets the letter, John will have to send a different one marked respectively for each of these 3 potential house numbers.

So, the lowest number of letters that John needs to send for Peter’s receiving letter is 3. Sending the letter to each of those potential viable (3570, 4900 and so on.) John will ensure that Peter does receive it regardless whether his particular 4 digit address ending in zero exists here or there on Tesla Street.