NumberProperties: Number Properties

In exams.forge: Support for Compiling Examination Tasks using the 'exams' Package

Number Properties

Description

• is_terminal checks whether x's can be expressed as a terminal fraction, basically divisor_25(denominator(x))

• divisor_25 checks whether all x's can be expressed as 2^x 5^y

• prime_numbers returns all prime numbers up to a limit

• primes prime factorization of x, returns a matrix with the power of each prime number

• has_digits checks whether the x's have only digits after the decimal point, basically abs(x-round(x, digits))<tol

• all_integer checks whether all x's are integer, basically all(has_digits(x,0))

Usage

divisor_25(x)

denominator_25(x)

is_terminal(x)

round_25(x)

prime_numbers(n, sieve = FALSE)

primes(x, min = 2)

has_digits(
  x,
  digits = 2,
  tol = 10^{
     -digits - 6
 }
)

all_integer(x)

only_digits(
  x,
  digits = 2,
  tol = 10^{
     -digits - 6
 }
)

is_term(x)

denom_25(x)

Arguments

x	numeric: values to test/check
n	integer: find all prime numbers up to n
sieve	logical: should in any case the Sieve of Eratosthenes be used to compute prime numbers (default: FALSE)
min	integer: the minimum prime number used (default: 2)
digits	numeric: number of digits to check (default: 2)
tol	numeric: max. deviation from the rounded x (default: 1e-6)

Value

logical

Examples

is_terminal(2/3)   # 0.6666... non-terminal
is_terminal(1/5)   # 0.2       terminal
divisor_25(1:25)
prime_numbers(100) # all prime numbers less equal 100
primes(1:20)       # prime factorization of 1 to twenty

exams.forge documentation built on Aug. 21, 2025, 5:41 p.m.