易如反掌

yìrúfǎnzhǎng
  1. easy as a hand's turn (idiom); very easy
  2. no effort at all

CEDICT

easy as ABC; simple as kiss your hand

Wiktionary

比喻事情非常容易做到。《北史．卷三八．裴佗傳》：「以國家威德，將士驍雄，汎蒙汜而揚旌，越崑崙而躍馬，易如反掌，何往不至。」《三國演義．第二二回》：「以明公之神武，撫河朔之強盛，興兵討曹賊，易如反掌，何必遷延日月。」也作「易如翻掌」、「易於反掌」。

重編國語辭典

Entry Composition

1 易 yì
  1. easy
  2. amiable
  3. to change
  4. to exchange
  5. prefix corresponding to the English adjective suffix "-able" or "-ible"
2 如 rú
  1. as
  2. as if
  3. such as
3 反掌 fǎnzhǎng
  1. lit. to turn over one's palm
  2. fig. everything is going very well.