We took my son, his wife and child to a restaurant of his choice on a Saturday nite. I asked for the check, which appeared abnormally high for 4 adults at about $12 a head.
I quietly told the waiter to go back and check. The hostess arrived and told me it was correct.
In a normal loud vice I protested the error of about $50 and insisted that they manually add up my tab.
I eventually got an apology, and charged the corrected amount.
Before charging ADD the bill and calculate an approximate total before asking.