The conservation claim binds to the intended before and after ledger. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The conservation ledger pins the exact before and after case
The ledger compares the 6 to 3 inertia change only with spin 4 to 8.
6×4=3×8
The before and after sources are part of the claim
The value 24 comes from both rendered products, not from a caption alone.