失之毫厘，差之千里

shī zhī háo lí , chà zhī qiān lǐ

a tiny lapse can lead to a huge mistake (idiom); a minor discrepancy leading to enormous losses

失

shī

to lose

之

zhī

(possessive particle, literary equivalent of 的[de5])

毫

háo

hair

厘

lí

one hundredth

，

,

差

chà

different

之

zhī

(possessive particle, literary equivalent of 的[de5])

千

qiān

used in 鞦韆|秋千[qiu1 qian1]

里

lǐ

li, ancient measure of length, approx. 500 m