That's a tricky one, but doable. Ideal is with a Seedsigner or ColdCard. They allow you to enter the words and will calculate a valid last word. Or, download the tool, https://iancoleman.io/bip39/, to a usb, load it on a device that has no internet, and it can calculate the last word. Or, use a hardware device to restore your seed and try 24th word until you find a valid one. Tedious, but will work after 256 tries on average.