90 = 12 + 3 + 45 + 6 + 7 + 8 + 9
90 = 9 + 8 + 7 + 6 + 54 + 3 + 2 + 1
90 = 8 × 3/6 + 1 × 27/54
90 = 0^1 + 1^8 + 2^7 − 3^9 + 4^5 + 5^6 + 6^0 + 7^4 + 8^3 + 9^2
90 = (11 − 1) × (11 − 1 − 1)
= 2 × 2 × 22 + 2
= 3 × (33 + 3)
= 44 + 44 + (4 + 4)/4
= 5 × 5 + 55 + 5 + 5
= 66 + 6 + 6 + 6 + 6
= 7 + 77 + 7 − 7/7
= 88 + (8 + 8)/8
= 99 − 9
90 = 3^2 + 9^2
90 = 1^2 + 2^2 + 2^2 + 9^2 = 1^2 + 2^2 + 6^2 + 7^2 = 1^2 + 3^2 + 4^2 + 8^2 = 2^2 + 5^2 + 5^2 + 6^2 = 3^2 + 3^2 + 6^2 + 6^2 = 3^2 + 4^2 + 4^2 + 7^2
Numbers k such that k^4 + 1 is prime. (65610001)
Number k such that k | 9^k + 9
Factors: 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90
Representations, Binary to Hexadecimal:
1011010_2
10100_3
1122_4
330_5
230_6
156_7
132_8
110_9
82_11
76_12
6c_13
66_14
60_15
5a_16
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