Two digit number with 7 as unit digit 7 are:
17, 27, 37, 47,57,67,77,87,97
we know that in 27 sum of digits =2+7=9
for 57=> 5+7=12
87=> 8+7=15
so 27,57 and 87 are divisible by 3
77=7*11 so 77 is divisible by 7 and 11
Thus 4 no are not prime
So the Prime number are:
17,37,47,67 and 97
17, 37, 47, 67, 97
0 Look at the product of the first 3 prime numbers: 2 x 3 x 5 = 30. Any number multiplied by 30 will have a 0 in the units digit. So, no matter how many prime numbers you are multiplying, if once you have a number ending in 0, all of the rest will end in 0.
there are 50 prime numbers between 1-100 and of them 2,3,5,7 are single digit so that would leave 46 double digit prime numbers between 1-100
Ten.
Only one positive prime number has a 5 in the ones digit. That prime number is 5. All other numbers with a 5 in the ones digit are composite because they will be divisible by 5.
17, 37, 47, 67, 97
There are 5 of them.
There are 21 two-digit prime numbers.
The prime numbers with a units digit of 1 in the range 1 - 121 are :- 11, 31, 41, 61, 71 and 101.......making 6 primes in total.
0 Look at the product of the first 3 prime numbers: 2 x 3 x 5 = 30. Any number multiplied by 30 will have a 0 in the units digit. So, no matter how many prime numbers you are multiplying, if once you have a number ending in 0, all of the rest will end in 0.
19 29 59 79 89 Five of them.
There are 17 such numbers.
There is no simple formula for that; I suggest you look up the prime numbers in a table of prime numbers, analyzing each prime number in the range 10-99 whether it fulfills this specific criterion.
An on-line prime number chart ended at 10007. There are many more charts available for download. So the answer is that there are many five digit prime numbers.
there are 50 prime numbers between 1-100 and of them 2,3,5,7 are single digit so that would leave 46 double digit prime numbers between 1-100
24 of them.
Ten.