In how many different ways can three letters be posted from seven different postboxes assuming no two letters can be posted from the same postbox?
Select the correct option:
A) 110
B) 210
C) 310
D) 410
E) 510
First letter could be sent from ANY of the seven postboxes - 7 (7 options);   Second letter could be sent from the SIX postboxes left - 6 (6 options);   Third letter could be sent from the FIVE postboxes left - 5 (5 options);   Total # of ways =7*6*5= 
<gadget id="calculator">7*6*5</gadget>
<output>210</output>
210   ANSWER:210
<result>B</result>
In how many different ways can three letters be posted from seven different postboxes assuming no two letters can be posted from the same postbox?