Please follow below simple steps to achieve your requirement.
Use workbook read range to get the column data you have to specify your column name in the range eg: B:B(if you have account number in the B column). it will give you all the values in the Account number column and store the data into a data table.
Use for each row activity assign your data table. And it will help you to loop one by one account numbers. To extract each account number use assign activity and use expression like CurrentRow(“Your Acct number column name”).tostring to get the account numbers one by one. please refer the below screenshot as you requested. thanks.
Please follow the suggestions from our members. And also for your question there is work around like below.
Use work book read range to get the dynamic row count. use range as “” so that it will extract all the rows with the data and store it in Data table suppose DT1.
RowCount=DT1.rows.count
Use the same step i mentioned in step1 this time use range “B1:B”+Rowcount.tostring