Antoine wants to convert millimeters into kilometers. which operation should he choose? he should multiply millimeters by 1,000. he should divide millimeters by 1,000. he should multiply millimeters by 1,000,000. he should divide millimeters by 1,000,000.ntoine wants to convert millimeters into kilometers. which operation should he choose? he should multiply millimeters by 1,000. he should divide millimeters by 1,000. he should multiply millimeters by 1,000,000. he should divide millimeters by 1,000,000.