`A` `=` `12 345 674` . `12 345 676`
`B` `=` `12 345 675` . `12 345 675`
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`A` `=` $12345674.12345676$
$=(12345675-1)(12345675+1)$
$=12345675^2-1$
`B` `=` $12345675.12345675=12345675^2$
$\text{Vì $12345675^2-1<12345675^2$ nên $12345674.12345676<12345675.12345675$}$
$\text{Vậy $12345674.12345676<12345675.12345675$}$