By preparing bank reconcialation statement

by preparing bank reconsilation statement reconciling 
the cash book balance with pass book balance this 
difference araises when
eg - cheques deposited but not yet collected
     cheques issued but not presented for payment
in simple words we can say that difference between cash 
book balance&pass book balance

Easy solution is do the Bank Reco. Compare the entires in 
our book with the bank statement and Vise - a - versa. 
Reason for differences :
1. Charges debited by bank but no entry in our books.
2. Cheques deposited but not cleared in bank.
3. Cheque issued but not presented in bank for payment.