you can say that 2/10 of every 10 integers is divisible by 5, so multiplying 2/10 by 100, giving you 200/1000 total integers are divisible by 5. half of all integers are odd, so divide 200/1000 by 2 is 100/1000, so you can correctly state that 100 odd integers under 1000 are divisible by 5.
There are no numbers that are divisible by 21 but not by 7 so the "or 21" part of the question can be ignored.There are 166 numbers between 1 and 1000 that are divisible by 6. However, 23 of those are also divisible by 7.So 166 - 23 = 143 numbers.
9000 integers.
193 of them are divisible by one (or more) of the given numbers.
8 of them.
There are 2001 numbers.
333 integers.
There are 2828 integers between 1000 and 9999.
There are 90 integers less than 1,000 that are divisible by 11.
666 integers.
There are 130 positive integers less than 1,000 that are divisible by seven but not divisible by 11
There are 128 integers between 100 and 1000 that are divisible by seven.
There are 1,000 positive integers between 1,000 and 9,999, inclusive, that are divisible by nine.
500 numbers in the range [1, 1000] are divisible by 2.
There are 544 positive integers less than 1,000 that are either divisible by two or by 11.
332
There are 333 of them - too many to list here.
130 numbers