80 = 1 × 2 + 3 + 45 + 6 + 7 + 8 + 9
80 = 9 + 8 + 7 + 6 + 5 + 43 + 2 × 1
80 = 0^2 − 1^9 − 2^6 + 3^7 − 4^8 + 5^1 + 6^0 + 7^3 + 8^4 + 9^5
80 = 4^2 + 8^2
80 = 2 + 5 + 73 = 2 + 7 + 71 = 2 + 11 + 67 = 2 + 17 + 61 = 2 + 19 + 59 = 2 + 31 + 47 = 2 + 37 + 41 (Sum of 3 distinct primes)
Numbers k such that k^4 + 1 is prime.
Moser-de Bruijn sequence: sums of distinct powers of 4
Numbers of edges of regular polygon constructible with unmarked straightedge and compass.
Factors: 1, 2, 4, 5, 8, 10, 16, 20, 40, 80
Eighty
Representations, Binary to Hexadecimal:
1010000_2
2222_3
1100_4
310_5
212_6
143_7
120_8
88_9
73_11
68_12
62_13
5a_14
55_15
50_16
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Undergraduate Texts in Mathematics
Graduate Studies in Mathematics
