If you schedule three follow-up appointments, each lasting 30 minutes, what is the total time?

• A. 60
• B. 120
• C. 150
• D. 90

Answer: (D)

When you have several equal-length blocks of time, multiply the length of one block by how many blocks you have to get the total. Each appointment is 30 minutes and there are three of them, so 3 × 30 = 90 minutes. That’s the total time, which is also 1 hour and 30 minutes. The other numbers would come from using different numbers of blocks (two blocks would be 60 minutes, four blocks would be 120 minutes, five blocks would be 150 minutes), which isn’t the situation here.