It means that you are talking about numbers that have more than one digit.
2, 3, 5, and 7 are the only one-digit prime numbers.
None. 3 digit numbers are not divisible by 19 digit numbers.
The basic idea is the same as when you estimate sums and differences of larger numbers (which may or may not be integers). You round the numbers to one or two decimal digits, then add them up.
3 digit numbers are lessthan 4 digit numbers
"Sum" requires at least two numbers. So there cannot be athree digit number that sums to anything.
The ratio of the number of one-digit prime numbers to the number of one-digit composite numbers is one to one. The one-digit prime numbers are 2, 3, 5, and 7. The one-digit composite numbers are 4, 6, 8, and 9. Therefor, the ratio is 4:4, which simplifies to 1:1.
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.
It means that you are talking about numbers that have more than one digit.
There are four of each.
2, 3, 5, and 7 are the only one-digit prime numbers.
No one-digit numbers are divisible by 10. 10 is divisible by 1, 2 and 5.
None. 3 digit numbers are not divisible by 19 digit numbers.
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.
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
The product of the ten one-digit numbers is 0.
Infinitely many. 12+11, 13+10, 14+9, ... , 22+1, 23+0, 24+(-1), 25+(-2), ... and then you have sums with numbers to one decimal place (dp) such as 11.6+11.4, and so on. Not forgetting numbers to 2 dp, 3, dp, 4, dp, ... , infinitely many dp. But these are only sums of two numbers. There are sums of 3 numbers, 4 numbers, ... infinitely many.