Graphical method (line segment diagram, network diagram/tree diagram, venn diagram and table, etc.). )
Using graphics to solve mathematical operations and showing the relationship between complex numbers vividly can solve problems faster and more accurately.
(1) line graph is a method to express the relationship between number and quantity with line segments.
(2) Venn's diagram is a graph that uses circles to represent a class of things. Generally speaking, Venn diagram is only used to include and eliminate problems.
Mantissa method
If the last digit of the option is different, the last digit of the original formula is calculated; If the last two digits of the options are different, the last two digits of the original formula are calculated.
substitution method
Substitute the options directly into the stem to verify the answer.