Here's how to create a Custom Summary Formula to return period-over-period data comparisons within a report.
These instructions use the Opportunities Object as an example, but the principles apply to all Salesforce reporting.
Lightning
Note: #Error! is returned anytime a formula is dividing by zero. If your formula errors in this way, the denominator in the fraction has returned "0."
Classic
Note: #Error! is returned anytime a formula is dividing by zero. If your formula errors in this way, the denominator in the fraction has returned "0."
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