first digit time second digit and second digit times first digit then repeat
There are 450 of them.
If you can repeat a digit, there are 27. If you can't repeat a digit, there are only 6.
10C2 = 45
There are 3 values (1, 2, 3) for each of the 4 digits. Therefore, there are 3*3*3*3 or 81 four digit numbers that can be formed.
No.
Since a Beprisque is a whole number that is consecutive and between a prime and a square, we look to the squares above 100 to begin our search. 121 is a square, but the the two odd numbers on either side of it (119 and 123) are not prime, so we check the next odd perfect square. (Why would we skip over 144?) 167 is prime and 169 is a square, so 168 is Beprisque, and is the first 3-digit Beprisque.
A 3 or 4 digit number.
There are 28706 such combinations. 5456 of these comprise three 2-digit numbers, 19008 comprise two 2-digit numbers and two 1-digit numbers, 4158 comprise one 2-digit number and four 1-digit numbers and 84 comprise six 1-digit numbers.
There are 9 1-digit numbers and 16-2 digit numbers. So a 5 digit combination is obtained as:Five 1-digit numbers and no 2-digit numbers: 126 combinationsThree 1-digit numbers and one 2-digit number: 1344 combinationsOne 1-digit numbers and two 2-digit numbers: 1080 combinationsThat makes a total of 2550 combinations. This scheme does not differentiate between {13, 24, 5} and {1, 2, 3, 4, 5}. Adjusting for that would complicate the calculation considerably and reduce the number of combinations.
There is no such ratio that applies for all single-digit and double-digit integers.
-2
72. (with the range of two digit numbers being from 10 to 99).
The answer will depend on how many digits there are in each of the 30 numbers. If the 30 numbers are all 6-digit numbers then the answer is NONE! If the 30 numbers are the first 30 counting numbers then there are 126 combinations of five 1-digit numbers, 1764 combinations of three 1-digit numbers and one 2-digit number, and 1710 combinations of one 1-digit number and two 2-digit numbers. That makes a total of 3600 5-digit combinations.
Highest 2-digit number = 99 Highest 1-digit number = 9 Highest possible sum from 2, 2-digit numbers = 198 Highest possible sum from 2, 1-digit numbers = 18
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!
It would help to know which digit. 0 appears in 9 numbers and each of the others in 18 numbers.