I need help with developing an Excel formula that finds any 4-digit numbers that have "stacking" digits (digits that are higher than the last e.g. 1234, 2356, 5679) without any duplicates of the digits. This is with the assumption that digits range from 0-9 and the first digit can be a zero. If you can also find a formula that finds 4-digit numbers with 3 recurring digits and 1 stacking digit (e.g. 3334, 7779, 4555), or 2 recurring digits with 2 stacking digits (e.g. 2234, 3455, 4556), or 2 pairs of recurring digits that do stack (e.g. 3344, 6688, 2288) then please also let me know.