handshake

Everyday

A handshake is when two people take each other's right hand and shake it, to say hello, goodbye, well done, or to agree. tree →

In the lessons

counting problems: each pair of people shakes hands once; in everyday life and manners: a firm friendly handshake when meeting an adult, at the end of a game to say «good game», or to agree a deal; phrases: «shake hands», «a firm handshake»

Examples

• 4 friends each shake hands with every other friend. tree →
• How many handshakes are there? tree →
• Each handshake is between 2 people. tree →
• 5 players make 10 handshakes. tree →
• The two teams lined up for handshakes after the match. tree →
• He greeted the head teacher with a polite handshake. tree →
• They sealed the deal with a handshake. tree →
• Some people bow or wave instead of a handshake. tree →

Note

For n people each pair once: 1 + 2 + … + (n − 1). Trap: n × (n − 1) counts each handshake twice, so divide by 2. 4 people make 6 handshakes; 5 make 10. Manners: look the person in the eye and say hello.