〜のに (for doing)
for (doing), in order to
Verb dictionary form + のに + 使う / 便利 / かかる / 必要
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Dictionary form + のに can also mean "for (doing)", describing what something is used for, how useful it is, or what it takes: このかばんは旅行するのに便利です, "this bag is handy for travelling"; 駅まで行くのに三十分かかる, "it takes thirty minutes to get to the station".
It goes with a small set of words: 使う (use), 便利 (handy), いい (good), 役に立つ (useful), かかる (take time or money), 必要 (necessary).
It's a different のに from "even though"; the words after it tell you which. And ために is for deliberate goals: 旅行するために休みを取った, "I took time off in order to travel".
Examples
このかばんは旅行するのに便利です。
This bag is handy for travelling.
駅まで行くのに三十分かかります。
It takes thirty minutes to get to the station.
このナイフはパンを切るのに使います。
This knife is for cutting bread.
家を買うのにお金がたくさん必要です。
You need a lot of money to buy a house.
日本語を覚えるのに、アニメは役に立ちます。
Anime is useful for picking up Japanese.