Mrs Morgan, the class's teacher, pinned numbers onto the backs of three children: Mona, Bob and Jamie.

"Now," she said, "Those three numbers add to a special kind of number. What is it?"

Michael put his hand up. "It's a square number," he answered. "Correct," smiled Mrs Morgan

"Oh!" exclaimed Mona, "The two numbers I can see also add to a square!"

"And me!" called out Bob, "The two numbers I can see add to a square too!"

"Oh dear," said Jamie disappointedly, "the two numbers I can see don't add to a square! It's either 5 too little or 6 too big!"

What numbers did the 3 children have on their backs?