91 = 12 + 22 + 32 + 42 + 52 + 62
91 = 1 + 2 + 3 + ... + 12 + 13
91 = 1 + 2 + 34 + 5 × 6 + 7 + 8 + 9
91 = 9 + 8 + 7 + 6 + 54 + 3 × 2 + 1
91 = 0^6 − 1^9 − 2^8 − 3^7 + 4^5 + 5^3 + 6^4 + 7^0 + 8^1 + 9^2
1 = (11 − 1) × (11 − 1 − 1) + 1
= 2 × 2 × 22 + 2 + 2/2
= 33 + (3 + 3/3)3
= 4 + 44 + 44 − 4/4
= 5 − 5 × 5 + 555/5
= 66 + 6 × 6 − 66/6
= 77 + 7 + 7
= 88 − 8 + 88/8
= 99 − 9 + 9/9
\({\displaystyle {\begin{matrix}\mathrm {Cabtaxi} (2)&=&91&=&3^{3}+4^{3}\\&&&=&6^{3}-5^{3}\end{matrix}}} \)
Maximal number of pieces obtained by slicing a torus (or a bagel) with n cuts: (n^3 + 3*n^2 + 8*n)/6, n = 7
Semiprime (Product of 2 Primes)
Factors: 1, 7, 13, 91
Representations, Binary to Hexadecimal:
1011011_2
10101_3
1123_4
331_5
231_6
160_7
133_8
111_9
83_11
77_12
70_13
67_14
61_15
5b_16
<--- --->
Undergraduate Texts in Mathematics
Graduate Studies in Mathematics
