There are several groups of numbers; [1,2,3] [4,5,6] [7,8,9] [10,11,12] please work out the sum of the three numbers in the 100th group

There are several groups of numbers; [1,2,3] [4,5,6] [7,8,9] [10,11,12] please work out the sum of the three numbers in the 100th group

The number of each group is three, and it is in order, so the number of group 100 is 301.302.303 and 906