The phrase 'it requires only one' is correct and usable in written English.
You can use it when you want to emphasize the fact that something needs very few elements to be achieved. For example, "Success in this venture requires only one thing - hard work."
In truth, after all of this tinkering the resulting soup remains on the meager side, but it requires only one more ingredient to turn it into a meal.
It requires only one electromagnet and two fan sheets with one magnet on each of them.
Our protocol is efficient and practical, because it requires only one pairing operation and five multiplications by each party.
This method preserves the extended stability property of the RKC method for solving ODEs, and it requires only one projection per step.
Furthermore, this P. aeruginosa protease assay improves upon existing assays because it is simple, it requires only one step, and even more significantly it is enzyme specific.
Comparability might be enough to make Humira competitive because it requires only one injection every two weeks, while Enbrel must be injected twice a week.
To protect its sales, Insmed had argued that its drug, Iplex, was superior to Tercica's drug, Increlex, because it required only one injection a day instead of two.
It required only one of the periodic droughts that customarily afflict Russia to bring about a massive famine.
All of those factors encouraged African Americans in Detroit to view the police as merely the occupying army of an oppressive white "establishment". In such a volatile atmosphere, it required only one provocative act by police to produce open revolt.
It required only one to two years before the shift took hold and the majority of the population created social media profiles.
This approach was especially valuable to families traveling from farther districts within the province, as it required only one monthly visit per family.
