Generate a Random Number with 7 Digits

Question

How can I produce a random number in a range from 1 million to 10 million?

rand(10) works, I tried rand(1..10) and that didn't work.

Accepted Answer

Take your base number, 1,000,000 and add a random number from 0 up to your max - starting number:

 1_000_000 + Random.rand(10_000_000 - 1_000_000) #=> 3084592

Answer 2

It's an instance method:

puts Random.new.rand(1_000_000..10_000_000-1)

Answer 3

I find this more readable:

7.times.map { rand(1..9) }.join.to_i

Answer 4

This will generate a random number between 1,000,000 and 9,999,999.

rand(10_000_000-1_000_000)+1_000_000

This works in 1.8.7 without any gems(backports, etc).

Answer 5

Or, in case performance is not an issue and you don't want to count zeros:

(0...7).map { |i| rand((i == 0 ? 1 : 0)..9) }.join.to_i

Answer 6

Another option with ruby 1.8.7 compatibility:

rand(9999999999).to_s.center(10, rand(9).to_s).to_i

6 Answers