Esteban's grandmother asked him how many children were on his soccer team. Since he knows that his grandmother loves a challenge, he replied, "After last Saturday's game, all of the children on my team exchanged high-fives with each of their teammates. When they were done congratulating each other, 150 high-fives had taken place." Esteban's grandmother replied that he must be mistaken. Esteban replied, "Oh, you're right! I transposed my digits. There were actually 105 high-fives."