“Well, that is done,” said Joanna.
“Divide by four, subtract half of the number first set down, and your answer will be six.”
“Oh, but how did you know that I put down sixty-four?” said Joanna.
“I didn’t,” said Jack.
“How could you tell the answer, then?”
“That’s for you to find out.”
This puzzle excited a great deal of curiosity. To add to the wonder of the scholars, Jack gave each time a different number to be added in, and sometimes he varied the multiplying and dividing. Harvey Collins, who was of a studious turn, puzzled over it a long time, and at last he found it out; but he did not tell the secret. He contented himself with giving out a number to Jack and telling his result. To the rest it was quite miraculous, and Riley turned green with jealousy when he found the girls and boys refusing to listen to his jokes, but gathering about Jack to test his ability to “guess the answer,” as they phrased it. Riley said he knew how it was done, and he was even foolish enough to try to do it, by watching the slate-pencil, or by sheer guessing, but this only brought him into ridicule.
“Try me once,” said the little C. C. G. W. M. de L. Risdale, and Jack let Columbus set down a figure and carry it through the various processes until he told him the result. Lummy grew excited, pushed his thin hands up into his hair, looked at his slate a minute, and then squeaked out:
“Oh—let me see—yes—no—yes—Oh, I see! Your answer is just half the amount added in, because you have——”
But here Jack placed his hand over Columbus’s mouth.