How many 4 digit words are possible by using English alphabet a to z with condition one alphabet

M4maths Previous Puzzles

06 May 2010 How many letter are possible?

How many 4 digit words are possible by using English alphabet a to z with condition
one alphabet is not allow more than twice consecutively ex- "aaab", "cccc" not allowed

OPtion

1) 456976
2) 455650
3) 456345
4) 331776
5) 358800
6) 234545
7) 453444
8) 355650
9) 546784
10) 1360

Solution

Total possible 4 digit character are = 26*26*26*26 = 456976
and 3 and 4 consecutive possible letters are = (26*2-1)*26 = 1326
so possible letters are 456976 - 1326 = 455650

Correct Option: 2 Best Solution (3)