She texted three people.

I have to call three times in all; , a total of 12 short messages will be sent.

Here we need to consider the influence of the arrangement order on the results:

1, three people communicate with each other once, and each person calls the others twice, but the results of A-to-B calls and B-to-A calls are the same, so the total number of calls is (2+2+2)÷2 = 3 times;

2. Four people send messages to each other, and each person sends messages to others three times. There is no order here. The result of texting Party B is different from that of texting Party B to Party A, so a total of 3+3+3 = 12 messages will be sent.

Extended data:

Basic counting principle and application of two commonly used arrays

1, addition principle sum classification counting method;

Each method in each class can accomplish this task independently; The specific methods in the two different methods are different from each other (that is, the classification is not heavy); Any method to accomplish this task belongs to a certain category (that is, the classification does not leak).

2. Multiplication principle and step counting method:

One method of any step can't complete this task, and only by continuously completing these n steps can this task be completed; Each step is independent of each other; As long as the methods used in a step are different, the corresponding methods to complete it are also different.