Divisible by 7 numbers between 100 and 6548

[nisarg]

How many and what is the sum of the numbers between 100 and 6548 divisible by 7?

[Guest]

I think 920 numbers
Sum 99820

We have number 100 - not devide 7
101 - not devide 7
102 - not
103 - not
104 - not
105 - yes. Do this with 6548, but degreese....
6548 - not
6547 - not
6546 - not
6545 - yes
So, we can know how many numbers between 105 and 6545. [tex]6545-105=6440[/tex] [tex]6440/7=920[/tex]
[tex]920[/tex] - number, what divisible by 7.
Second question) Sum. If you remember[tex]S=\frac{(a_1+a_2)*n}{2}[/tex]; [tex]a_1=105, a_2=112[/tex] [tex]S=\frac{(105+112)*920}{2} = 460 * 217 = 99820[/tex]
[tex]99820[/tex] - sum.....This is all. Made by ThunderDark