2 sentences for 算计 (suàn​ji — scheme)

1. 他竟然在背后算计自己的好朋友。

   tā jìng​rán zài bèi​hòu suàn​ji zì​jǐ de hǎo péng​you.

   He actually plotted against his own good friend behind their back.

   Source: Dong Chinese Dictionary

2. 那个人阴险狠毒，总是背地里算计别人。

   nà gè rén yīn​xiǎn hěn​dú, zǒng​shì bèi​dì​li suàn​ji bié​ren.

   That person is insidious and ruthless, always plotting against others behind their backs.

   Source: Dong Chinese Dictionary