Ether GWEI confusion

hi there can someone help me please on an equationish

1. I went onto the crypto testers website and they have stated that to see roughly how much we pay in gas fees for an ether transfer we take the number of gas paid, in this case 26 and then multiply it by the gas limit which here is 250000 we get 6,5,00000 which is about 6.5 million gwei which is roughly 0.0065 which when I convert to pounds is £10.14 which is definitely not correct.
2. However if i multiply 26 gwei (gas price) by the gas used for the transaction which was 52089 is 1354314 gwei which when converted is 0.00135431 eth which converted to GBP is 2.11 which roughly is what the dollar amount is

Is this correct? the second one? yet the guide said use the first formula. Like I wont know how much gas is used for a tnx surely until after a tnx is done?

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