Answer

For a teenager who wants a good life and sharp बुद्धि, there is no single universally fixed Bhaktamar gatha prescribed for this purpose in Jain tradition. The safest and most devotional practice is to recite the entire Bhaktamar Stotra daily with श्रद्धा.

If you want to begin with one simple practice, many Jain families choose a verse from the Bhaktamar for wisdom, guidance, and inner strength—but this is based more on traditional belief than on a strict scriptural rule.

Explanation

Bhaktamar is powerful because of:

• भक्ति
• नियमितता
• शुद्ध भाव
• संयमित जीवन

For a teenager, the most important things are:

• daily recitation
• good conduct
• respect for parents and teachers
• truthfulness
• avoiding bad habits
• disciplined study

If you are asking for a practical routine, you can do:

• 1 recitation of Bhaktamar Stotra daily
• or one gatha daily with ध्यान and श्रद्धा
• then pray for good बुद्धि, good habits, and a pure life

Spiritual Understanding

In Jain Dharma, real बुद्धि is not only memory or intelligence. It also means:

• right understanding
• right thinking
• self-control
• discrimination between right and wrong

So along with Bhaktamar, a teenager should also develop:

• अध्ययन
• विनय
• संयम
• सत्संग
• अहिंसा

Takeaway

If you want one simple answer: recite Bhaktamar daily, preferably the whole stotra. If you want, I can also tell you a simple daily Jain prayer routine for students and teenagers.