All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
If the heirs of this deceased are only those mentioned above, the inheritance should be distributed as follows:
The mother gets one-sixth of the inheritance due to the existence of the children of the deceased, as Allaah Says (what means): {And for one's parents, to each one of them is a sixth of his estate if he left children.}[Quran 4:11]
What remains after the allotted share of the mother should be distributed among the direct sons and daughters by Ta’seeb (by virtue of having a paternal relation with the deceased and not having an allotted share, so they get what is left after the allotted shares have been distributed); the male twice the share of the female as Allaah Says (what means): {Allaah instructs you concerning your children: for the male, what is equal to the share of two females.}[Quran 4:11]
However, the son's children do not get anything from the inheritance because they are prevented by the existence of the direct children, even though it is favorable for the heirs to maintain kinship ties with them by giving them something thereof, in accordance with Allaah's Saying (which means): {And when [other] relatives and orphans and the needy are present at the [time of] division, then provide for them [something] out of the estate and speak to them words of appropriate kindness.}[Quran 4:8]
Therefore, the inheritance, in principle, should be divided into 6 shares, and it could also be regulated and divided into 66 shares: the mother gets one-sixth which is 11 shares, each male gets 10 shares, and each female gets 5 shares.
Allaah Knows best.