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Is 1 Steem Power really equal to 1 Steem, or does that rate change based on something?

If you are using the GUI wallet(steemit) then 1 STEEM POWER equals to 1 STEEM. Right now in your wallet you have 18,9 STEEM POWER that is equal to 18,9 STEEM. The CLI wallet is another story and I don't know exactly how the conversion is done.

If you created this account in STEEMIT and you recieved 10 free STEEM POWER you need to wait until your STEEM POWER is 5X or 10X more(can't remember the exact number) until you can power down.