Taweez and number 786 is Indo-Pak creation and has nothing to do with Islam religion. Nowhere in Quran or Hadith such things are mentioned and is not prescribed by Prophet Muhammad (SAWS).
Taweez (Emulets):
If any person wear a Taweez and thinks it will protect him from bad omen and trouble than it’s a Shirk; as only Allah can protect you from any dangers.
Also we have seen people going in toilets wearing taweez which is disrespect to Quranic verses written in it. Will you take Quran with you in toilets? Any form of taweez like wearing thread, bangles, kada etc. are unislamic.
People apply kajal or black color thread and bangles to new born babies thinking it will protect the baby from bad omen or evil eye which is Jahalat and unislamic. It is Allah who will protect you from every danger; so seek help and protection from Allah and read duas mentioned in quran for protection.
Nay, Allah is your protector, and He is the best of helpers. (Quran- Al Imran 3:150)
786:
does not mean ‘bismillahirahmaniraheem and is used by ignorant people.
Due to our ignorance we have used these numbers believing them to be sacred. Numerology is neither a language nor does it help in preserving or spreading the teachings of the Qur’aan. The sole purpose of Numerology is to make charms and amulets, which are used as a part of the religion to avert misfortune and evil eye which is unislamic.