A matching pool total does not mean every indexed sample was equally represented. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
An unbalanced pool can have the same total
The rows 8,6,10 still sum to 24.
8+6+10=24
The imbalance remains visible at the source rows
Index B has 6 reads while index C has 10. The ledger does not hide that difference.