How to assign leads and cases using round robin?

use case:

assign them equally to the existing members.

For eg, if there are 3 members, assign the first lead to member1, second lead to member2 and so on.

solution:

create two custom fields - Auto number that begins with 1

and a formula field that would generate the round robin id, type - number.

Formula is mod(value({!<auto number field>},3)+1

note - assuming there are 3 members so the divisor is 3.

set the assignment rule - if round robin id is 1 assign to member1 and so on.