The number of cards for a 47-story house is therefore

2 + 2 + 3 + 2 + 3^{.}2 + 2 + 3^{.}3 + ... + 2 + 3^{.}(n-1) + ... + 2 + 3^{.}(47-1) ---------------------- 47^{.}2 + 46^{.}47/2 x 3 = 3337

Source: Berrondom, Marie

Categories: Number sense, Arithmetic

[Top | Problem]