Asked by jen
An elf has a staircase with 10 steps to climb. Each step it takes can cover either one stair or two stairs. In how many ways can the elf climb the stairs?
Answers
Answered by
Reiny
5 Doubles === 1 way
4 Doubles, 2 Singles === e.g. DDSSDD
number of ways = 6!/(2!4!) or C(6,4) = 15
3 Doubles, 4 Singles === C(7,3) = 35
2 Doubles , 6 Singles === C(8,2) = 28
1 Double , 8 Singles === C(9,1) = 9
10 Singles === 1
total = 89
4 Doubles, 2 Singles === e.g. DDSSDD
number of ways = 6!/(2!4!) or C(6,4) = 15
3 Doubles, 4 Singles === C(7,3) = 35
2 Doubles , 6 Singles === C(8,2) = 28
1 Double , 8 Singles === C(9,1) = 9
10 Singles === 1
total = 89
Answered by
karina
i don't understand how its 89 ways!
how about 20 stairs, and N stairs? what would be the equation for that?
how about 20 stairs, and N stairs? what would be the equation for that?
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