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It is indeed ambiguous. I just took "another" to mean one more prime number and not as a "different" prime number, but I see how it can be interpreted either ways.
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Question clearly states , the 3 digit number starts with one prime number and ends with another prime number

2,3,5,7 are possible primes here.


ones ending with 2 can be have 30 combinations ( ending with 3 = 10, ending with 5 =10, ending with 7 =10, middle digit can be anything from 0 to 9)

similarly we can have 30 combinations for each of 3 , 5, 7 .

so 30*4 =120.

Answer is D
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If you were to break down how you are to read this question and what are the first things that should come to mind, after reading the answers, ive gotten a little lost. I understand that that primes should be 2,3,5,7. But after that im lost, please treat this as an idiots guide:)
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If you were to break down how you are to read this question and what are the first things that should come to mind, after reading the answers, ive gotten a little lost. I understand that that primes should be 2,3,5,7. But after that im lost, please treat this as an idiots guide:)

First digit can be 2,3,5,7
Second digit can be 0,1,2,3,4,5,6,7,8,9
Third digit can be 2,3,5,7

So; by the slot method, first and 3rd digit both have 4 choices and the 2nd one, 10
Total = 4*10*4= 160.

Apparently, that's not actually meant in the question. It means to say that the first digit is a prime number and the 3rd digit is a different prime number(different from one used in the hundred's place)

Thus;
Hundreds place: 4 choices
Tens place: 10 choices
Units place> 3 choices

4*10*3 = 120 three digits numbers that start with a prime number and end with a different prime number.
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