Is number 4 considered a symbol of violence, revolution, explosion and aggression? Is the fear associated with this number in society really rational?

Yes that is because number 4 is associated with the most explosive planet in astrology, Rahu.
It is a very hot, flammable and bright planet, due to its fatalistic nature it can neither be controlled nor can it be predicted what it will do in life. It is known for its aggression, abruptness and mysterious nature and can bring a lot of ups and downs in human life.

If this number starts appearing repeatedly in someone's life and he finds small and big events of his life influenced by this number, then he should understand that bad luck or misfortune has come to him in the form of this number, which will continuously eclipse his happiness and joy.

The cruelty and barbarity of number 4 i.e. planet Rahu is seen even more when it comes close to number 5 i.e. planet Mercury, whose association with auspicious planets works to increase its auspiciousness, on the other hand, its association with malefic planets indicates further increase in its troubles.

To understand this, suppose a person is born on 4th, 13th, 22nd or 31st and the single number of his vehicle or house is 5, then in such a situation number 4 will have an even greater effect on him which can prove fatal.
Similarly, when these dates (4th, 13th, 22nd and 31st) fall on Wednesday, then also the person should be careful, in such a situation also there is a possibility of an unexpected incident.
If a person wants to reduce the sorrows and sudden calamities in his life, then he should stay away from number 4 in his life.

And this can happen only when he does not choose the dates 4, 13, 22, 31 to complete his main tasks and plans even by mistake.

He should also avoid choosing these dates for any kind of celebration or function etc. because if he does so, then the grip of this number on him will become very weak due to which his main events will gradually stop being affected by this number and he will be able to come out of the circle of misfortune.

Even if someone's house, shop or building is on rent, then it should not be influenced by number 4 at all because such a house or shop may be inhabited by negative energy which can cause him many problems. He may have to suffer financial loss there, may hear or see such news or incidents Which are heart-breaking.
It is often seen that in such buildings and shops, a person always suffers from feelings of unrest and dissatisfaction.

In this regard, I would even say that if someone is born on 4th, 13th, 22nd, 31st of any month, then also he should avoid using number 4 on his behalf, instead it would be better to use numbers 1, 2 and 7. 

On dates formed by these numbers (1, 2 and 7) the person can complete his important tasks with full confidence.

Remember, Number 4 i.e. Rahu is known for its fatalistic tendency and is related to such incidents in life which seem totally unexpected or impossible, such as a person suddenly becoming bankrupt, getting entangled in court cases, becoming a victim of a violent explosion, accident or fire, etc.

This is why any object or person influenced by this number can cause great trouble and misfortune for anyone.
Though sometimes this number can bring sudden advancement or progress, yet it should not be chosen as auspicious because the end result of this number often puts the person in unusually difficult situations.

But only in one case, the misfortune and inauspicious things related to this number reduce significantly when a person is born on 4, 13, 22 or 31 and the last digit of his name i.e. the total is 1, 2, 4 or 7.
For example, I have selected a person named Ramesh Singh whose date of birth is 13.03.1996.

R A M E S H             S I N G H
(2+1+4+5+3+5)  +  (3+1+5+3+5)
2O  +  17 = 37 = 3+7= 10 = 1+0= 1

as above, I have worked out this name to find its single digit by using cheldean number system which I have already featured on my blog.
Here, the last digit of this complete name is 1

Date of birth is 13.03.1996, 

so last digit of his birth no. is 1+3= 4
So, number 4 will not have any bad effect on this person rather he will be a successful person from the worldly point of view because 1 and 4 are interchangeable numbers and are compatible with each other.

Finally, I would like to say again that any person should carefully check the numbers of everything related to him, be it a car, bike, taxi, plot or even a mobile.

In which house of the horoscope the Sun can give the best results to a person?

According to astrology, Sun represents soul and father.
People who have a strong Sun in their horoscope  they do not like any kind of hindrance, restriction or advice in their work and are very determined and ambitious and have a tendency to be leaders everywhere, be it any department or business.
Moreover,  father's life span,  position and prestige is increased
And the native becomes a sharer in the happiness of his father.

So let us discuss those four specific houses of the horoscope where Sun can give the most auspicious results.

When the Sun is placed in the third, sixth, tenth or eleventh house of the birth chart, then it is in its strongest position and becomes the provider of extremely auspicious results to the person.

Third House --
When it is in the 3rd house it makes the person very courageous, sharp minded, sweet spoken and clean hearted. He gets the facilities of high class vehicles and servants etc.
But the number of brothers is less. If the Sun is not in its own sign then the happiness of the brother and the family decreases and if this Sun is also affected by malefic planets then there is a fear of poison, fire, skin disease and bone breakage. There may be untimely death of a brother or sister or else a distance is created between them due to some kind of ideological differences etc.
No matter what the reason is, in such a case, the person's brother and sister may be unhappy; they may also be deprived of the happiness of having children.

However, Sun in the 3rd house makes the native wealthy and materialistic.

Sixth house --
Due to the presence of Sun in the sixth house, the person becomes famous, victorious over enemies, royal, highly respected people follow his advice.
He may own a high class vehicle and enjoy special luxuries. The influence of Sun in this place makes a person very talented, intelligent and diplomate.

If the Sun in the sixth house is associated with or is  aspected by auspicious planets And if the lord of the sixth house is also in a good position and there is auspicious effect on it then person becomes strong and courageous. In front of him the power of enemies becomes weak, no matter how big the circle of enemies is.
On the contrary, if the sixth lord is weak then destruction of the enemy is certain, but it is not auspicious for the father.

Tenth House -
The presence of the Sun in the tenth house makes a person healthy, intelligent and a brave warrior.
Such a person is very courageous, famous and familiar with the ways of earning money but at the same time he loves the society of saints.
If 2 or 3 auspicious planets are aspecting the Sun at this place then the person is a favourite of the king, adept in all works, famous and valiant.
Even if Sun is in its exalted sign or own sign then the person becomes famous and renowned.
But if the Sun is associated with or aspected by any malefic planet, then the person has to face obstacles in his work and he may deviate from his goal.
He may even become mean and corrupt and get involved in anti-social activities and become a part of infamy.

Eleventh House --
When the Sun is placed in the eleventh house, the person is healthy, has an attractive body, is endowed with knowledge, wisdom and morality. He gets fame due to his good deeds, gets the favour of highly respected and royal people, but he also has many enemies.
If the Sun of this place is in its exalted sign or own sign, is under the influence of auspicious planets and is also strong in the Navamsha and other sections then such a person can get a prestigious administrative post  and can also become a great politician.