Nils Andersen Røsaasen - Birth and death dates?

My research on Ancestry indicates DOB: 5/7/1804 and DOD: 8/10/1853. His name is sometimes spelled “Niels.” I’m not sure why the Rosaasen surname reference but I have that as well.

OK, so for right now then, I'll change the DOB to May, 7, 1804 and leave the DOD the same as it is. Farm book shows the first name as Nils, so I'll leave that as is too.

All the church records I have found so far shows Røsaasen as his address, not his last name

Baptism may 10 1804, Niels https://www.digitalarkivet.no/kb20061106020310

First marriage Maria Olsdatter: https://www.digitalarkivet.no/view/327/pv00000001371600
Second marriage Karine Johannesdatter: https://www.digitalarkivet.no/view/327/pv00000001928015

His burial: https://www.digitalarkivet.no/view/267/pg00000000373755

1825 Anne https://www.digitalarkivet.no/view/255/pd00000005092425
1829 Ole https://www.digitalarkivet.no/view/255/pd00000003788321
1832 Kari https://www.digitalarkivet.no/view/255/pd00000003790836
1837 Anders https://www.digitalarkivet.no/view/255/pd00000003794196

With his second wife:
1847 Anne Marie https://www.digitalarkivet.no/view/255/pd00000004459782
1849 Johanne Mathea https://www.digitalarkivet.no/view/255/pd00000004460967
1852 Albrect https://www.digitalarkivet.no/view/255/pd00000004463013

1854 (after he died) Nils https://www.digitalarkivet.no/view/255/pd00000004464394

Farm name generally accompanies given names, no?

That is often a construction done by genealogists and bygdebok authors to keep track of a family, - you can see for yourself that Røsaasen is not a part of the name in the church records - later generations (in this case the son Nils as an example) started to use the farm name as a family name, all over Norway as as a part of the naming law of 1923 which stopped the use of patronymic names and start using a family name, - a change that started around 50 years earlier

This is so helpful. Thank you!

Michael Jospeh Walsh, - I expect that you add add the children and the second wife to this tree, - you have all the details above.

Beklager, nei. I only have interest in my wife's direct lineage.