X + (X + 2) + (X + 4) + (X + 6) + (X + 8) + (X + 10) = 888
6X + 30 = 888
6X = 858
X = 143
======
X + 2 = 145
X + 4 = 147
X + 6 = 149
X + 8 = 151
X + 10 = 153
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143 + 145 + 147 + 149 + 151 + 153/6
= 148
======Which you knew, but now you know how to get there. ( 888/6 is the quick way )