how many four digits numbers are formed such that the digits are in decreasing order
Choose the correct choice from the following answers
A) 210  B) 220  C) 230  D) 240  E) 250
START with 3 = 3_ _ _. You can fill in with digits 0,1,2. Hence 3C3 = 1   START with 4 = 4_ _ _. (0,1,2,3). hence 4C3= 4   START with 5, you have (0,1,2,3,4) to fill in the blanks behind 5, hence 5C3 = 10   START with 6, 6C3=20   7... = 7C3 = 35   8...=8C3 = 56   9...= 9C3 = 84   so ans=1+4+10+20+35+56+84= 
<gadget id="calculator">1+4+10+20+35+56+84</gadget>
<output>210</output>
210   210NSWER:210
<result>A</result>
how many four digits numbers are formed such that the digits are in decreasing order