Question

How many numbers are divisible by both 5 and 7 between 10000 and 95240?

Answer 1

1st no divisible by 5 after 200 is 205 last no divisible by 5 before 800 is 795 
therefore a=205, an=795 d=5 
an= a + (n-1)d 
795= 205 + (n-1)5 
n=119 therefore 119 nos b/w 200 and 800 are divisible by 5 
similarly for 7 
1st no divisible by 7 ahead 200 is 203 last no divisible by 5 before 800 is 
therefore a=203, an=798 d=7 
798= 203 + (n-1)7 
n=86 therefore 86 nos b/w 200 and 800 are divisible by 7




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