Mnemonic Device:

• stationAry is pArked cArs, stationEry is Envelopes and pEns.

Variations:

• StationAry – StAnd still
• StationEry – PEns, PEncils
• Remember the middle letters of “car” and “pen,” to know which, stationary or stationery, is correct.

Explanation: mnemonic device to distinguish the words STATIONERY/STATIONARY