What are the first common multiple 18 and 16?

Answer 1

16 has multiples > 32 48 64 80 96 112 128 144 160

18 has multiples > 36 54 72 90 108 126 144 162 180

so answer is 144

144 has multiples > 288 432 576 720 864 1,008 1,152 1,296 1,440

and so on ...