A Tunnel Boring Machine (TBM) and a crane together cost $1,100,000.

The TBM costs $1,000,000 more than the crane.

How much does the crane cost?

Many people respond by saying that the crane must cost $100,000. Is this the answer that you came up with? If so, it is incorrect.

If the crane cost $100,000 and the TBM costs $1,000,000 more than the crane, then the TBM would cost $1,100,000 for a grand total of $1,200,000.

The correct answer to this problem is that the crane costs **$50,000** and the TBM costs — a $1,000,000 more — $1,050,000 for a grand total of $1,100,000.

The catch here is that, people seem to unconsciously substitute the “more than” statement in the problem (the TBM costs $1,000,000 *more than* the crane) with an absolute statement (the TBM costs $1,000,000) and when you do that, you get $1,200,000 combined.