Search results
Results from the WOW.Com Content Network
20: It is divisible by 10, and the tens digit is even. 360: is divisible by 10, and 6 is even. The last two digits are 00, 20, 40, 60 or 80. [3] 480: 80 It is divisible by 4 and by 5. 480: it is divisible by 4 and by 5. 21: Subtracting twice the last digit from the rest gives a multiple of 21.
d() is the number of positive divisors of n, including 1 and n itself; σ() is the sum of the positive divisors of n, including 1 and n itselfs() is the sum of the proper divisors of n, including 1 but not n itself; that is, s(n) = σ(n) − n
2012 – The number 8 × 10 2012 − 1 is a prime number [10] 2013 – number of widely totally strongly normal compositions of 17; 2014 – 5 × 2 2014 - 1 is prime [11] 2015 – Lucas–Carmichael number [12] 2016 – triangular number, number of 5-cubes in a 9-cube, Erdős–Nicolas number, [13] 2 11-2 5; 2017 – Mertens function zero, sexy ...
In the past 500 years, there was no leap day in 1700, 1800 and 1900, but 2000 had one. In the next 500 years, if the practice is followed, there will be no leap day in 2100, 2200, 2300 and 2500 ...
For example, 6 is highly composite because d(6)=4 and d(n)=1,2,2,3,2 for n=1,2,3,4,5 respectively. A related concept is that of a largely composite number , a positive integer that has at least as many divisors as all smaller positive integers.
The year's position in the cycle is given by the formula ((year + 8) mod 28) + 1). Years 2, 8 and 19 of the cycle are common years beginning on Wednesday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Wednesday.
The number 18 is a harshad number in base 10, because the sum of the digits 1 and 8 is 9, and 18 is divisible by 9.; The Hardy–Ramanujan number (1729) is a harshad number in base 10, since it is divisible by 19, the sum of its digits (1729 = 19 × 91).
Many properties of a natural number n can be seen or directly computed from the prime factorization of n.. The multiplicity of a prime factor p of n is the largest exponent m for which p m divides n.