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a flight of stairs has 10 steps.a person can go up the steps one at a time ,two at a time,or any combination of 2's and 2's.find d total number f wayz in which d person can go up d stairs??? plz give me complete soln for dis....cuz i got d ans bt prob z m nt sure about the way i solved it!! ans is:89do reply....plzz!!
Dear Shalini,
There are 10 steps, so following cases are possible:
10 single steps =1
1 double steps, 8 single steps = 9!/8! =9
2 double steps, 6 single steps = 8!/6!2!=28
3 double steps, 4 single steps = 7!/4!3!=35
4 double steps, 2 single steps = 6!/4!2!=15
5 double steps = 1
Total=89
Hope this helps.
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