Act out the problem. Sometimes it helps to physically act out the problem. For example, there are 5 people in your study group, and each person initiates a handshake with every member one time. How...

Act out the problem. Sometimes it helps to physically act out the problem. For example, there are 5 people in your study group, and each person initiates a handshake with every member one time. How many total handshakes will there be? There will be 20 handshakes total, because each person shakes hands 4 times (because you cannot shake your own hand). Thus, 5 people times 4 handshakes equals 20 total handshakes. You multiply the total number of people times one number fewer for the handshakes.