lifted up his hand and passed it along the gap between the stones which formed the edge of the square. Then he moved his hand inside the square and this was when the real magic happened. He touched a number and it shone as if there were a bright light being projected onto it. When he touched a second number, the two of them changed places.
He jumped back from the wall, startled. “What was
that?”
“Only magic will let you through,” Gelio quoted.
“But there must be millions of possibilities,” objected Paidia. “How are we going to solve it?”
“I have an idea,” said Muko. “If we add up all the numbers and divide by the number of rows, we'll have the sum of the numbers that there should be in each row and column. Do you see?”
While Muko was explaining his idea, Amartia had stepped quickly up to the wall and touched a couple of numbers. There was a loud CLANG and the magic square appeared before their eyes. All the numbers in the square and the square itself shone brightly – so brightly that the children were forced to close their eyes and turn away.