Double entry also allows for the accounting equation (assets = liabilities + owner's equity) to always be in balance. In our example involving Advertising Expense, the accounting equation remained in balance because expenses cause owner's equity to decrease. In that example, the asset Cash decreased and the owner's capital account within owner's equity also decreased.
A third aspect of double entry is that the amounts entered into the general ledger accounts as debits must be equal to the amounts entered as credits.
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