Zero.
8
The first 8 digit number is 10,000,000, the last is 99,999,999 which means there are 90,000,000 8 digit numbers
The smallest three-digit number divisible by the first three prime numbers (2, 3, and 5) and the first three composite numbers (4, 6, and 8) is 120.
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.
The product of two digit numbers is always greater than either.
10 because 10 is the first 2 digit number out of all numbers.
There are only two prime numbers that are consecutive numbers, 2 and 3. Their product is 2 x 3 = 6. The first prime numbers are 2, 3, 5, and 7 and the only two consecutive prime numbers whose product is a single digit are 2 and 3. (The next two consecutive prime numbers, 3 and 5, have a two-digit product.)
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.
3 digit numbers are lessthan 4 digit numbers
The question is a bit ambiguous: "the sum of the product ... " does not seem to make sense. The first 5 digit number is 10000 the first 5 digit multiple of 6 is 10002 Their product is 100020000. I am not sure what to sum, though.
5.
8
It is 0.
In any two-digit multiplication sum, for example, 3 x 2 = 6, the first digit is called the multiplier, the second digit is called a multiplicand, and the third digit, the answer, is the product.
The first 8 digit number is 10,000,000, the last is 99,999,999 which means there are 90,000,000 8 digit numbers
The unit's digit is 0. That is true for the product of the first n primes provided n>2.The unit's digit is 0. That is true for the product of the first n primes provided n>2.The unit's digit is 0. That is true for the product of the first n primes provided n>2.The unit's digit is 0. That is true for the product of the first n primes provided n>2.
Assuming that the first digit of the 4 digit number cannot be 0, then there are 9 possible digits for the first of the four. Also assuming that each digit does not need to be unique, then the next three digits of the four can have 10 possible for each. That results in 9x10x10x10 = 9000 possible 4 digit numbers. If, however, you can not use the same number twice in completing the 4 digit number, and the first digit cannot be 0, then the result is 9x9x8x7 = 4536 possible 4 digit numbers. If the 4 digit number can start with 0, then there are 10,000 possible 4 digit numbers. If the 4 digit number can start with 0, and you cannot use any number twice, then the result is 10x9x8x7 = 5040 possilbe 4 digit numbers.