His pen ran rapidly over the paper, and in a minute or two he handed Dan the following form of acknowledgment:
"New York, Sept. 15, 18—.
"For value received I promise to pay to Alexander Grant five dollars on demand with interest."
"Now," said Mr. Grant, "put your name at the bottom."
Dan did so.
"I added 'with interest,' but only as a form; I shall require none."
"I would rather pay it, sir."
"That may be as you please. How much will six per cent. interest make it amount to in a year?"
"Five dollars and thirty cents," answered Dan, promptly.
"Good! I see you have not forgotten what you learned in school."
"I have ciphered through cube root," said Dan, with some pride. "I am not sure whether I remember that now, but I could do any sum in square root."