Afarmer was planning seeds in a garden he planted 203 radish seeds and 506 turnip seeds. to the nearest hundred how many seeds did he have left total

Well, first you would start by adding the 203 and the 506! And that = 709.
Automatically you can round to 700, because the 9 is under 50, the halfway mark! So, your answer would be 700 planting seeds (a lot of seeds if you ask me ;) ) 
Hope I helped you :)

The decimal expansion would be .27 repeated