As already pointed in the comments section, one idea to carry out this task is using the EXISTS operator inside the WHERE clause, by checking all records from mastertable whose "account_number" can be found inside table1.

SELECT * 
FROM mastertable m
WHERE EXISTS(SELECT 1 
             FROM table1 t 
             WHERE m.account_number = t.account_number)

Output:

Check the demo here .

select a.account_number,sum(account_balance) from master_table a
inner join table1 b on a.account_number=b.account_number
group by a.account_number

You can insert Base data with the following statements:

drop table if exists table1
create table table1(person_number int,  account_number int)

insert into     table1(person_number,account_number)  values(11 ,1)
insert into     table1(person_number,account_number)  values(12 ,2)
insert into     table1(person_number,account_number)  values(13 ,3)
insert into     table1(person_number,account_number)  values(14 ,4)
insert into     table1(person_number,account_number)  values(15 ,5)
drop table if exists master_table
create table master_table(account_number int,   account_balance int)

insert into     master_table( account_number,   account_balance)values(1,   238989    )
insert into     master_table( account_number,   account_balance)values(2,   4889895   )
insert into     master_table( account_number,   account_balance)values(3,   68897     )
insert into     master_table( account_number,   account_balance)values(4,   298729    )
insert into     master_table( account_number,   account_balance)values(5,   387745    )
insert into     master_table( account_number,   account_balance)values(6,   354655    )
insert into     master_table( account_number,   account_balance)values(7,   553455    )
insert into     master_table( account_number,   account_balance)values(8,   35545     )