Question

I am a number between 60 and 100. My ones digit is two less than my tens digit. I am a prime number. What number am I. Explain.

Answer 1

Find the number in where it is between 60 and 100.
Its ones digit is 2 less than its tens digits. And it is a prime number.
=> thus the digit is 2 digit since it has ones and tens place value.
Let’s assign a variable to use. Let a be the value of ones and b the value of tens
ones = A – 2
tens = y
So let’s find the number between 60 to 100 that the value of ones is 2 less than the value of tens
=> 64
=> 75
=> 86
=> 97
Now, we have possible answers. However, prime numbers are not divisible and is not even numbers.
So the answer is 97.

Answer 2

Let's name the digit:

x- ones digit
y - tens digit

we know that x=y-2.

Now, y can be 6,7,8,9 (the number is between 60 and 100 (so depending on your understanding of "between", 0 is also possible. but then the number would have to have -2 as its ones digit, so in any case, it's not possible).

So the possibilities with x=y-2:

64
75
86
97
Out of those 64 and 86 are even, so they can't be prime.
75 has 5 in its ones number: it's divisible by 5.

so the correct answer is 97.