Add up verb – Add up in number or quantity. Tell and add up are semantically related. in list topic. In some cases you can use "Tell" instead a verb "Add up", when it comes to topics like add, count.
The reason behind this is simple: when you focus too much on behavior to tell if someone is lying, you stop focusing on the best way to telltheir story simply doesn't add up.
Some people think Israeli PM Yitskhak Rabins assassination is not quite what the authorities tell them, as some details dont entirely add up, and a considerable portion of what the Shabak did beforehand is still classified.
They then tell their story to the authorities, get praised as heroes and jet to a nice warm, extradition-free island to enjoy their money before anyone realizes that a thing or two doesn't add up.