24 * 60 / 1 = 1’440 Catalyst blocks a day
24 hours a day * 60 minutes per hour / blocktime in minutes = blocks created per day
A day consists of 24 hours and each hour has 60 minutes. This means that there are 1’440 minutes per day. With a block time of 1 minute (60 sec block time), you will have 1’440 blocks a day.
So with 1/1’440 of the hash power you should get an average of one block per day. From there on, you can now calculate how much percentage you contribute to the overall network hashrate and how many blocks you would find per day.
Lets assume, that the network hashrate is 2’000’000 h/s. With 1’440 blocks a day, you would need around 1’389 h/s to find one block per day.
The difficulty is just a factor that makes sure, that the average block time stays the same even though the network hashrate might change. If the hash power increases, the difficulty will raise as well. And the other way round it gets easier to compute a block’s solution when the available hash power gets lower. So it always leads to a value close to one minute.