Tav

Tav is the last letter in the Hebrew alephbet.
The pictograph looks like a cross.
The meaning of this letter is; a mark, a sign, a cross, mark of ownership, seal, covenant, join two things together, the last.
Tav has a value of 400.

To spell the word 'tav', two letters are used, a tav and a vav, which literally translates as, ' the sign of the nail ' ( a reference to jesus )
In Ezekiel 9 v4-6 we find reference to the letter tav;
He said to him," Walk through the streets of Jerusalem and put a mark ( tav) on the foreheads of all who weep and sign because of the detestable sins being committed in their city" Then I heard the LORD say to the other men, " Follow him through the city and kill everyone whose forehead is not marked..... But do not touch anyone with the mark ( tav)....
V4 the righteous people were given a mark.
V6 the mark served as protection for the righteous ones.

Those who are made righteous, those who belong to Christ , are protected.
2 corinthians v22 He has commissioned us, and He has identified us as His own by placing the Holy Spirit in our hearts as the first installment that guarantees everything He has promised.
Ephesians 1v13 And when you believed in Christ, He identified you as His own by giving you the Holy Spirit, whom He promised long ago.
The Holy Spirit is God's seal of ownership, promise and protection over us.

The word for seal/sign in Hebrew is formed from the letters aleph,vav, tav. It's literal meaning is ,' the strong leader, nailed to the cross '. Jesus is the seal, the blood of the Lamb, we have been bought by His blood, He has marked us out for Himself and we are joined to Him.

Words associated with the letter tav.
Brit- meaning covenant. Litteral meaning, my son of the covenant or the son of the cross.
Tavah , our word for ark. Litteral meaning, house of the covenant or sealed house.

Those who are in a covenant relationship with God , Rest in the saving work of Jesus ( the name Noah means , Rest )

Value 400;
40 × 10 ; 40 in Jewish thinking represents a peroid of testing . 10 represents the full manifestation. Jesus is the final outworking for the Jewish nation of God's plan and purposes for them.
5×8×10; 5 represents the grace of God. 8 represents resurrection life. 10 the full manifestation of these, ie Jesus
8x50; 8 reference to new life, new birth in Christ. 50 , the year of Jubilee when slaves were set free. We were slaves to sin but in Jesus we have been set free.