9 = 12345678 × 9
9 = 9 + 87 − 65 − 43 + 21
9 = 0^6 + 1^9 + 2^8 − 3^7 + 4^5 + 5^4 + 6^3 + 7^0 + 8^2 + 9^1
9 = 1! + 2! + 3!
93 = 13 + 63 + 83
9 = 4 ÷ 4 + 4 + 4 = 44 ÷ 4 − √4
9 × 0 + 1 = 1
9 × 1 + 2 = 11
9 × 12 + 3 = 111
9 × 123 + 4 = 1111
9 × 1234 + 5 = 11111
9 × 12345 + 6 = 111111
9 × 123456 + 7 = 1111111
9 × 1234567 + 8 = 11111111
9 × 12345678 + 9 = 111111111
8 = 2^3 and 9 = 3^2 are the only consecutive powers, (Mihăilescu's theorem / Catalan's Conjecture )
Number of ordered pairs of integers (x,y) with x^2+y^2 < 2^2
Numbers k such that 2^k + 9 is prime. (521)
Number k such that (11*10^k + 19)/3 is prime
Integer k such that 10^k+21 is prime. (1000000021)
Number that is the sum of 9 positive 10th powers.
Number of ways of arranging 4 lines in the affine plane.
Number of meaningful differential operations of the 1- order on the space R^9.
Number of distinct products i*j*k for 1 <= i <= j < k <= n, n = 4
Semiprime (Product of 2 Primes)
Semiprime s such that s-/+2 are primes.
Factors: 1, 3, 9
Representations, Binary to Hexadecimal:
1001_2
100_3
21_4
14_5
13_6
12_7
11_8
10_9
9_11
9_12
9_13
9_14
9_15
9_16
Undergraduate Texts in Mathematics
Graduate Studies in Mathematics
