反掌

fǎnzhǎng
  1. lit. to turn over one's palm
  2. fig. everything is going very well.

CEDICT

  1. to be very easy to accomplish
  2. to turn over one's palm

Wiktionary

翻轉手掌。比喻事情的容易。《漢書．卷五一．枚乘傳》：「變所欲為，易於反掌，安於太山。」唐．杜甫〈觀公孫大娘弟子舞劍器行〉：「五十年間似反掌，風塵傾動昏王室。」也作「反手」。

重編國語辭典

Entry Composition

1 反 fǎn
  1. contrary
  2. in reverse
  3. inside out or upside down
  4. to reverse
  5. to return
  6. to oppose
  7. opposite
  8. against
  9. anti-
  10. to rebel
  11. to use analogy
  12. instead
  13. abbr. for 反切 fǎnqiè phonetic system
2 掌 zhǎng
  1. palm of the hand
  2. sole of the foot
  3. paw
  4. horseshoe
  5. to slap
  6. to hold in one's hand
  7. to wield

Containing this entry

易如反掌 yìrúfǎnzhǎng
  1. easy as a hand's turn (idiom); very easy
  2. no effort at all
易於反掌 yìyúfǎnzhǎng see 易如反掌 yìrúfǎnzhǎng