Convert decimal number to rational

By default, literal numbers are represented in rational form:

say 0.75.as_frac          #=> 3/4
say 0.518518.as_frac      #=> 259259/500000
say 0.9054054.as_frac     #=> 4527027/5000000

Additionally, Num(str) can be used for parsing a decimal expansion into rational form:

'0.9054054 0.518518 0.75'.split.each { |str|
    say Num(str).as_frac
}

Output:

4527027/5000000
259259/500000
3/4

For rational approximations, the Number .rat_approx method can be used:

say 0.518518.rat_approx.as_frac    #=> 14/27
say 0.9054054.rat_approx.as_frac   #=> 67/74