How many numbers between 400 and 800 are divisible by 4,5 and 6

Dear aman

Take the lcm of those three numbers(4,5,6) which is equal to 60. The number which is divisible by 60 nearer to the number 400 is 420(a) then the last number nearer to 800 is 780(a_n). This is in A.P. then the last term(a_n) is equal to 

a_n=a+(n-1)d              where d is equal to 60

780=420+(n-1)60

360=(n-1)60

6=n-1

n=7

Therefore, the number of numbers divisible by 4,5 and 6 are 7

If you need to know the values you can just add up 60 to first nearer number(420) 

Those numbers are 420,480,540,600,660,720,780.