What mass of KCl is needed to prepare a 100mL with a concentration of 1.00 x 10^-3mol.L^-1?

Question

The question is in the title, and the answer is asking for Mass in grams, im not exactly sure how to do it. Please help!

Answer 1

100 ml x 1 L/1000 ml = 0.100 L

1.00x10^-3 mole/L x 0.100 L = 1.00x10^-4 moles needed

Molar mass KCl = 74.55 g/mol

mass KCl needed = 1.00x10^-4 moles x 74.55 g/mol = 7.46x10^-3 g KCl = 7.46 mg KCl