How many mL of 12M HCl is needed to create 350mL of 0.125M HCl?

Answer 1

x ml of 12M HCl = 12x milimoles
350 ml of 0.125M HCL = 43.75 milimoles

43.75=12x
x=3.6458

Answer 2

I agree with Shubh but s/he used too many significant figures in the result. You're allowed two places (from the 12M number)[that's assuming the post did not omit zeros after the 12]. So I would round to 3.6 mL. If that is REALLY 12.0 M then I would round to 3.65 mL.