Question

Fran thinks of a two digit number. The firs digit is 6 more than the second digit, and the number is prime. What number did fran think of

Answer 1

Answer: The number which Fran is thinking about is 82 or 93.

Explanation:

A two-digit number can be written as:

a*10 + b

Where a and b are single-digit numbers.

We know that:

"the first digit is 6 more than the second digit"

then:

a = b + 6

And we know that the second digit is a prime number.

Then we can have:

b = 2

b = 3

b = 5

b = 7

Now let's try with these different options.

if b = 2, then:

a = 2 + 6 = 8

Then the number is:

8*10 + 2 = 82

If b = 3, then:

a = 3 + 6 = 9

Then the number is:

9*10 + 3 = 93

if b = 5, then:

a = 5 + 6 = 11

But a needs to be a single-digit number, then b can not be 5 or larger.

Then the only two possible numbers are:

82 and 93.

So the number which Fran is thinking about is 82 or 93.