Bought this over the weekend and we have had fun playing it this morning. Helps kids to see numbers in different ways.
There is a 12 sided dice which you toss to get a number and  there are also 5 six sided dice. The object is to try to find as many combination of numbers with the 5 die to give you the number on the 12 sided dice.
For example:
The number on my 12 sided dice is 11
The 5 numbers on the other die are 1,5,6,2,4
Various math combinations I can have are:
1) 6+5=11
2) 5+4+2=11
3) 6+4+1=11

Source: Math Dice