Please paraphrase the following sentence for me. Thanks  But an accurate number but its in the 50s of thousands. ?

Technically it could mean 20000 to 90000 or even 10001- 99999.

Normally it would mean 20 or 30 000.

People normally say "tens of thousands."  50,000 ; 100;000 ; 150,000 <- as you say is a very awkward big gap ... but in geology, taxes, costs in a big business, population, etc people will say "hundreds of thousands" to get the intensity across

That's not a sentence. You have two conjunctions as if you have two clauses, but there's only one verb. No one says "50s of thousands". If it's multiple of 50, then it's in the hundreds of thousands range. Are you estimating a number?

The exact number is not known, but it is well over 100 thousand.

The number is approximately 150 thousand. 

The sentence makes no sense

and is

therefore

impossible to paraphrase.

not certain of the purpose of the first but.  Also some issue whether you mean "On the order of 50 thousand" or " a number than can be expressed in terms of some number of fifty-thousands".

Compare "about four hundred" with "measuring in the hundreds".  About four hundred means it is somewhere near 400.  "In the hundreds" though, means some unknown number of hundreds that might be quite a large range (something like 100-1500, perhaps, even, as all those rounded numbers in that range can be expressed as "hundreds").  If the upper end rolled over about 1500, the switch to thousands would be expected, depending on the situation.

Most of us do not count in groups of 50 thousands, so it would be a very rare thing to suggest that a value is some multiple of 50,000s.  tens of thousands, perhaps, but never fifties of thousands.

If you mean a number is about 50,000, or on the order of fifty thousand, or in the ballpark of 50,000, then you should say so.  If you mean it is a strict multiple of 50,000, then you should say it is a multiple of 50k.  If you mean it is a number measuring in the many tens of thousands (which might be what you mean) then that is probably how you should say it.