+: plus 加号；正号
1+1读作：one plus one
－: minus; negative 减号；负号
2|1读作：two minus one
|3读作：minus three或negative three
2|读作：two minus negative three
: plus|minus sign 正负号
1 读作：plus or minus one
: multiplied by ; times 乘号
23 读作：two multiplied by three 或 two times three
: pided by 除号
42读作：four pided by two
=: equals; is equal to 等于号
1+1=2读作：One plus one equals two.
或 One plus one is equal to two.
: is not equal to 不等于号
ab读作：a is not equal to b
≌: congruent to 全等（两个图形形状相同、大小相等）
△ABC≌△DEF读作：Triangle ABC is congruent to Triangle DEF.
: approximately equal to 约等于号
3310 读作：Three multiplied by three is approximately equal to ten.
: is less than 小于号
12读作 One is less than two.
: is greater than 大于号
21读作：Two is greater than one.
≮: is not less than 不小于号
3≮2读作：Three is not less than two.
≯: is not greater than 不大于号
2≯4 读作：Two is not greater than four.
: is less than or equal to 小于或等于号
23读作：Two is less than or equal to three.
: is greater than or equal to 大于或等于号
54读作：Five is greater than or equal to four.
