SOLUTION: How many natural numbers upto 990 are divisible by 5 and 9 both but not by 7 ?

Algebra ->  Divisibility and Prime Numbers -> SOLUTION: How many natural numbers upto 990 are divisible by 5 and 9 both but not by 7 ?      Log On


   

Question 1046566: How many natural numbers upto 990 are divisible by 5 and 9 both but not by 7 ?
Answer by ikleyn(52871) About Me  (Show Source):
You can put this solution on YOUR website!
.
How many natural numbers upto 990 are divisible by 5 and 9 both but not by 7 ?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

990%2F%285%2A9%29 = 22 natural numbers are divisible by 5 and 9 both.


Of them, 3 are divisible by 7: 45*7 = 315,  2*(45*7) = 630,  and 3*(45*7) = 945.


22 - 3 = 19.


Answer.  19 natural numbers.