The magnitude of a vector is the length of the vector. It is also known as the modulus of the vector. For any vector of the form <a,b>, the length is equal to sqrt(a^2+b^2). Note how this follows from the pythagorean theorem.
Step-by-step explanation: 11x12 because one of them will be the one shaking hands with everyone else so he would have gotten 11 hands shaked so everyone would have gotten their hands shaked 11 times