800guy wrote:How many integers less than 1000 have no factors (other than 1) in common with 1000?
(1) 400
(2) 410
(3) 411
(4) 412
(5) None of the above
from diff math doc. oa coming after some people respond with explanations
So we need numbers that have factors other than 2 or 5..... that wuld be equal to.. total- ( numbers with 2 or 5 as a factor )
Now, the number of integers that have 2 as a factor and less than 1000 is 499.....
now while counting factors of 5 we do not have to include numbers like 10,20,30... bcoz they are already included in the list of integers with 2 as a factor... so we only consider the odd multiples of 5... ie 5,15,25... which wuld be equal to 100.. therefore tha answer is 999-( 499+100) = 400.. therefore the answer is A....
