>>334 Ruby
require 'bigdecimal'
[3, 4, 5, 7].each{|i|
n = 1000*i - 1
puts "N = %i => %i"%[i, ("%.#{n}f"%BigDecimal(i).sqrt(n)).count(?0)]
}


N = 3 => 2956
N = 4 => 3999
N = 5 => 4956
N = 7 => 6954