using the digits 0,1,2,2,3 how many numbers greater than 20000 can be made ?

Assuming digits are to be used only once then as long as the first digit is greater than 1, any number formed will be greater than 20000:
3*4*3*2*1=72

How many words of 4 letters can be formed with the letter a,b,c,d,e,f,g and h. If e & f are always include, letters are not repeated.

(2)(1)(6)(5)=60

miles,don.tameka,and rosa set in the last row of desk. each day they sit in a different order. how many days can they do this before the repeat the setting pattern?

4!=24 
24 days

the total number of ways of forming groups by taking any number from n distinct objects is- a)2^n, b)2^n +1, c)2^n -1, d)none of these

we don't count the empty set so its 2^n-1

How many different ways can the name Kemanna be arranged?

7 letters, 2 letters repeated twice: 
 



:)