i've mistakenly pasted "2.5" in address field submitted a withdrawal request. can i get my coins back since the address is an invalid or the coin will be sent? I'm afraid i may loose my coins.
If I understand you correctly, you inputted wrong address ("2.5") to a withdrawal form somewhere.
In general if this request triggers a transaction then it can't be reverted anymore. But if it was just some online form and the data goes to a company processing the information you may ask them to stop the process. It really depends on where you input the information.
Depending on where and how you submitted this request it may vary how "2.5" will be interpreted - if the request went through it's probably parsed into some unaccessible address. Perhaps into 0x2500000000000000000000000000000000000000 and if that's the case you could check its transactions for example here: https://etherscan.io/address/0x2500000000000000000000000000000000000000 (there are no transaction currently).