LET

Assigns named variables within a formula. Improves readability by replacing repeated expressions with meaningful names. Also improves performance — each variable is calculated once regardless of how many times it is referenced.

=LET(name1, value1, [name2, value2, ...], calculation)

=LET(
  rate, TaxRate,
  subtotal, SUM(OrderItems[Price]),
  subtotal * (1 + rate)
)

=LET(
  days, NETWORKDAYS(StartDate, TODAY()),
  IF(days > 30, "Late", "On Track")
)