If you have a column with an identity value and is a clustered index you could select max(id) from the table.
You can also use this script to check the row count, page count and more of your tables.
t.NAME AS [TableName Database],
--i.name as indexName,
sum(a.total_pages) as TotalPages,
sum(a.used_pages) as UsedPages,
sum(a.data_pages) as DataPages,
(sum(a.total_pages) * 8) / 1024 as TotalSpaceMB,
(sum(a.used_pages) * 8) / 1024 as UsedSpaceMB,
(sum(a.data_pages) * 8) / 1024 as DataSpaceMB
sys.indexes i ON t.OBJECT_ID = i.object_id
sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
sys.allocation_units a ON p.partition_id = a.container_id
t.NAME NOT LIKE 'dt%' AND
i.OBJECT_ID > 255 AND
i.index_id <= 1
t.NAME, i.object_id, i.index_id, i.name, p.[Rows]
if your tables has tons of indexes it might show your rows per indexes also, you might have to tweak the script a little bit, this script i think is widely known, can't recall source but i didn't made it, it have helped me quite a lot.