write a query to get parent with max no of child records?

I have a number field on Account, on this I have written a validation rule saying number should be always < 10,000. Now I have a workflow field update on same and it’s updating with 15,000. Now user is trying to insert 12,000. What is the result??

write a query to fetch 99th record amon 100 records in a object?

write a query to fetch 99th record amon 100 records in a object?