Try a trivia question like this to reinforce percentages: "If 9 in 10 dentists recommend this toothpaste and 1,400 dentists were surveyed, how many recommend the toothpaste?" First, your kid will need to figure out the percentage of recommendations: 9/10 = 90%. Then, he or she will need to apply that percentage to the 1,400.So 90% * 1,400 = 1,260.