cardinality/rows column in the explain plan

I am looking at an explain plan with set autotrace on.

Table C has 53,000 rows. When I query dba_tables.num_rows it states that there are 53,000 rows. How can I have 'rows' of 1634 on a full table scan? Shouldn't it be all the rows in the table since Oracle is doing a full table scan?

I get teh same number when I look at the cardinality column in the 'explain plan for'. I had though that Oracle got the rows for a full table scan from dba_tables.num_rows? I guess not.

| Id  | Operation                          | Name                  | Rows  | Bytes | Cost (%CPU)| Pstart| Pstop |
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|   0 | SELECT STATEMENT                   |                       |     1 |    60 | 31780   (1)|       |       |

|   1 |  SORT AGGREGATE                    |                       |     1 |    60 |            |       |       |

|   2 |   TABLE ACCESS BY LOCAL INDEX ROWID| TABLE A               |     1 |    22 |     4   (0)|       |       |

|   3 |    NESTED LOOPS                    |                       |  2986 |   174K| 31780   (1)|       |       |

|   4 |     HASH JOIN                      |                       |  9506 |   352K|  3176   (4)|       |       |

|   5 |      TABLE ACCESS FULL             | TABLE B               |   211 |  3587 |   229   (6)|       |       |

|   6 |      TABLE ACCESS FULL             | TABLE C               |  1634 | 34314 |  2947   (4)|       |       |

|   7 |     PARTITION RANGE ITERATOR       |                       |     1 |       |     3   (0)|   KEY |   KEY |

|   8 |      INDEX RANGE SCAN              | TABLE_A_IDX01         |     1 |       |     3   (0)|   KEY |   KEY |

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