This looks like a Math question, actually it is an Epiphany tradition called Chalking the door.
20 and 19 stands for the year 2019. C, M, B stands for the names of the three magi, Caspar, Melchior and Balthasar. The plus sign is actually a symbol for the cross †.
Some variations also put “20*C+M+B+19”, where the star stands for the star of Bethlehem.
CMB can also be the abbreviated form of the Latin blessing “Christus mansionem benedicat“, which means, “May Christ bless this house”.
The LaTeX code for it can be:
20\dagger C\dagger M \dagger B\dagger 19
Singapore Maths Tuition 
Reblogged this on Tuition Database Singapore.
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