The left board if you add each group of numbers, the sequence is 8, 9, 10, etc except for 100.
It totals 1 so it is the odd man out.
On the right board if you add each group, they are all even numbers except for 427.
It totals 13 which makes it the odd man out.
So the answer is 100427.
Special thanks to Kim for this solution! :)
Proceed to the next level!