The "empirical formula weight" for CH_{2}O is 30.0

1) 30.0 / 30.0 gives 1, so the molecular formula is the same as the empirical formula: CH_{2}O

2) 60.0 / 30.0 gives 2, so the molecular formula is twice the empirical formula: C_{2}H_{4}O_{2}

2) 180.0 / 30.0 gives 6, so the molecular formula is six times the empirical formula: C_{6}H_{12}O_{6}