im pretty sure you had to take the excess number moles of hcl away from the original which was 0.015-something like 0.0014, so 0.0136 moles of hcl reacted with the CaCO3, then mass = 0.0136x100.09 or something like that, so about 1.36 grams i got. but everyone getting o.6 has got me worried...