30, abundant number. Abundant number : 12, 18, 20, 24, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 112, 114, 120, ... (sequence A005101 in the OEIS).
30 = 2 × 3 × 5 = 12 + 22 + 32 + 42
305 = 55+105+115+165+195+295
30 = 3 982 933 876 6813 − 636 600 549 5153 − 3 977 505 554 5463 .
30 = 12345 × 6 + 7 + 8 + 9
30 = 98 + 7 − 6 − 5 − 43 − 21
30 = 0^0 + 1^9 + 2^6 + 3^7 − 4^8 + 5^3 + 6^2 + 7^1 + 8^4 + 9^5
30 = (1 + 1 + 1) × (11 − 1)
= 22 + 2 × (2 + 2)
= 3 + 33
= 4 × (4 + 4) − (4 + 4)/4
= 5 × 5 + 5
= 6 × 6 − 6
= 77 − 7 × 7 + (7 + 7)/7
= 8 + (88 + 88)/8
= 999/9 − 9 × 9
230 - 1 = 3 × 3 × 7 × 11 × 31 × 151 × 331
1030 - 1 = 3 × 3 × 3 × 7 × 11 × 13 × 31 × 37 × 41 × 211 × 241 × 271 × 2161 × 9091 × 2906161
30=2x3x5 is a Giuga number. 30/2 - 1, 30/3 - 1, 30/5 - 1
If m and n are integers then mn(m^4 − n^4) is always divisible by 30
Sphenic number: Product of 3 distinct Primes, (List)
Number of Partitions of 9
Numbers k such that 2^k + 9 is prime
Number k such that k! - 1 is Prime
Number k such that the Woodall number kx2^k - 1 is prime. 30x2^30 - 1 = 32212254719.
Number of vertices in a hexagon when n internal hexagons are drawn between the 6n points that divide each side into n+1 equal parts (n= 2 )
Number of paths with 3 turns when light is reflected from 4 glass plates
Numbers of edges of regular polygon constructible with unmarked straightedge and compass.
Factors: 1, 2, 3, 5, 6, 10, 15, 30
Representations, Binary to Hexadecimal:
11110_2
1010_3
132_4
110_5
50_6
42_7
36_8
33_9
28_11
26_12
24_13
22_14
20_15
1e_16
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Graduate Studies in Mathematics
