The only other single-digit number higher than 5 which is a Prime number is 7 - 9 is equal to 3 squared, and is thus not a prime number.
679 is the product of the largest single-digit prime number and the largest two-digit prime number.
A single digit prime number
Any prime number greater than 10 is an odd number but cannot end in 5 as this makes it divisible by 5. Therefore the ones digit of any prime number greater than 10 must be 1, 3, 7 or 9.
29
23
The largest single digit prime number is 7.
3, 5, or 7
679 is the product of the largest single-digit prime number and the largest two-digit prime number.
16
A single digit prime number
Its impossible, there are only 5 single digit numbers that are not prime
89 is a prime number between 70 and 100 that has the ones digit one greater than the tens digit.
Any prime number greater than 10 is an odd number but cannot end in 5 as this makes it divisible by 5. Therefore the ones digit of any prime number greater than 10 must be 1, 3, 7 or 9.
Probably 73.
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Prime numbers greater than 10 will only end in 1, 3, 7 or 9.