. In a certain 2- digit prime numbers when you exchange the 2 digits, you get a prime number. How many such numbers can you find ? Write them
Answers
Answer:
we can find 4 such them
in the prim number
Answer:
There are only 2 such numbers:-
13 + 18 = 31
79 + 18 = 97
The logic actually lies in interpreting the question one information at a time.
Okay, firstly, we are given that a 2-digit prime number is to be considered. That should narrow down your value set to 21 numbers (there are 15 prime numbers between 1-50 and 10 prime numbers between 51-100, in all 25).
Next up, and the most important aspect of the question, "18 is added to this number..."
Just this much is enough to get your machine running. What I mean by that is you got to think something out of the box here.
If we add 18 to a 2-digit number, would the number such formed, have a tens digit 1 more than the original number or 2 more?
Yes, absolutely correct, 2 more! What does this imply?
THAT THE DIFFERENCE BETWEEN TENS AND UNITS DIGIT OF THE NUMBER IS "2"
How many 2-digit prime numbers are there?
13 and 31
79 and 97
Hope this helps ya! Peace out