Question

Mental Arithmetic: work the following exercises in your head. Do not calculate with a pencil or paper. Do not use a decimal. Think of the number seven. Now add eight to it. Now add four more. Now subtract nine. Now add three. Your answer is _____.

Answer 1

13 is your answer.
7+8=15
15+4=19.
19-9=10
10+3=13

Answer 2

The answer is 13 because it is