19.38×39+193.8×1.7+1.938×440 123×456÷ 789÷456×789÷123 大家知道这怎么简便吗?能列出来吗?

1 19.38X39+193.8X1.7+1.938X440
=19.38X39+19.38X17+19.38X44
=19.38X(39+17+44)
=19.38X100
=1938
2 123X456 / 789 / 456 X789 / 123
=123X456X789/(789X456X123)
=1