How many 2-letter "words" consist of two different letters arranged in alphabetical order? (Any two letters together is considered a "word.")
Notice that "a" could come first and be matched with 25 letters {the rest of them} for a total of 25 words
'b' could come first and be matched with 24 letters for a total of 24 words
"c" could come first and be matched with 23 lettters for a total of 23 words
etc........
So....this appears to just be the sum of the first 25 integers = [26 * 25] / 2 = 325
Hey....Melody and I agree on something!!!
any earlier letter then z
any earlier letter then y
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ab
25*1+24*1+23*1 + ..... +2*1+1
25+24+23+22+ +1
1+2+3+.......+25
this is an AP
a=1 d=1 n=25
Sn=(n/2) (a+L)
S_25 = 12.5(1+25)=12.5*26 = 325
I think that there are 325 possibilities.
Notice that "a" could come first and be matched with 25 letters {the rest of them} for a total of 25 words
'b' could come first and be matched with 24 letters for a total of 24 words
"c" could come first and be matched with 23 lettters for a total of 23 words
etc........
So....this appears to just be the sum of the first 25 integers = [26 * 25] / 2 = 325
Hey....Melody and I agree on something!!!