A short simple chemistry calculation please help?

Question

Any help is appreciated =)

An ionic compound forms when calcium (Z=20) reacts with iodine (Z=53). If a sample of the compound contains 8.98×1019 calcium ions, how many iodide ions does it contain?

Answer 1

The comound of calcium with iodine is going to be calcuim iodide: Calcium is +2; iodine is -1;

Ca + I2 >>> CaI2

Since there will be 2 iodines for each calcium, there will be 2 x 8.98 x 10^19 Iodine ions or 1.796 x 10^20 ions