3 13 23 43 53 73 83 103 113 163 173 193
Chat with our AI personalities
Yes
For any integer greater than 5, where the units digit is 5 then that number can be expressed as the product of n and 5. As such, the number is composite. Therefore all numbers in the range 150 to 200 that have a units digit of 5 are composite,.
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.
In every 100 there are 10 numbers that have a units digit of 2 and 10 with 7, making 2 with 2 or 7. Between 0 and 1000 there are 10 hundreds, making 10 × 20 = 200 such numbers. BUT 2 and 7 are less than 10, so there are two less such numbers, making 200 - 2 = 198 such numbers.
Oh, what a lovely question! If we're looking for 2-digit numbers where the one's digit is greater than the ten's digit, we simply need to think about the possibilities. There are 36 such numbers, ranging from 12 to 98. Just imagine all the happy little numbers waiting to be discovered!