68 = 1 × 2 + 3 × 4 + 5 × 6 + 7 + 8 + 9
68 = 9 + 8 + 7 + 6 + 5 + 4 × 3 + 21
68 = 0^4 + 1^8 − 2^6 − 3^9 + 4^7 + 5^5 + 6^3 + 7^1 + 8^0 + 9^2
68 = (1 + 1) × (11 × (1 + 1 + 1) + 1)
= 2(2+2+2) + 2 + 2
= ((3 + 3)3 − 3)/3 − 3
= 4 + 4 × 4 × 4
= 5 + (55/5 + 5)/(5 + 5)
= 66 + (6 + 6)/6
= 77 − 7 − (7 + 7)/7
= 88 − 8 − (88 + 8)/8
= 9 × 9 − (99 + 9 + 9)/9
Moser-de Bruijn sequence: sums of distinct powers of 4
Numbers of edges of regular polygon constructible with unmarked straightedge and compass.
Representations, Binary to Hexadecimal:
1000100_2
2112_3
1010_4
233_5
152_6
125_7
104_8
75_9
62_11
58_12
53_13
4c_14
48_15
44_16
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