How many prime numbers less than 100 are there that when divided by 5 leaves an odd remainder?

Question

What is a number that
when divided by 10 leaves a remainder 9 and
when divided by 9 leaves a remainder 8,
when divided by 8 then leaves a remainder 7,
and similarly till 1 ?

What is the Number ?

Answer 1

The only possible odd remainders from dividing number by 5 seem to be 1 and 3. The remainder of dividing by 5 in 10-based notation depends only on the last digit since every non zeroth power of 10 is divisable by 5.
From all digits from 0 to 9 only 1, 3, 6 and 8 would give the remainder of 1 or 3.
Since primes beside 2 must all be odd numbers, then all primes ending with 1 and 3 seem to be the only primes which when divided by 5 leave an odd remainder.
Hence for primes less than 100 they would be

3, 11, 13, 23, 31, 41, 43, 53, 61, 71, 73, 83

Answer 2

2,3,11,13,23,31,41,43,53,61,71,73,83are only prime no. Which leave odd reminder when divided by 5.