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📖 Dictionary
A bilingual glossary of math terms — read English textbooks without getting stuck.
A
- absolute value绝对值
- How far a number is from zero, always positive or zero.
- acute angle锐角
- An angle smaller than 90°.
- area面积
- The amount of space inside a flat shape.
- average平均数
- The sum of values divided by how many values (also called the mean).
B
- bar chart条形图
- A chart that uses bars of different heights to compare values.
C
- coefficient系数
- The number multiplied by a variable, like the 3 in 3x.
- common denominator公分母
- A shared denominator of two or more fractions.
- composite number合数
- A whole number with more than two factors, like 12.
- circumference周长（圆）
- The distance around a circle: C = 2πr.
D
- decimal小数
- A number with a decimal point, like 3.14.
- denominator分母
- The bottom number of a fraction — how many equal parts the whole has.
- diameter直径
- A straight line across a circle through the center: d = 2r.
- dividend被除数
- The number being divided, the a in a ÷ b.
- divisor除数
- The number you divide by, the b in a ÷ b.
E
- equation方程
- A math sentence with an equals sign, true for certain values.
- equivalent fractions等值分数
- Different fractions that name the same amount, like 1/2 and 2/4.
- estimate估算
- A sensible guess close to the exact answer.
- even number偶数
- A whole number divisible by 2.
- exponent指数
- How many times a base is multiplied by itself, the 3 in 2³.
F
- factor因数
- A whole number that divides another exactly, 3 is a factor of 12.
- fraction分数
- A part of a whole, written as numerator over denominator.
G
- gradient (slope)斜率
- How steep a line is: rise over run, m = Δy/Δx.
H
- hypotenuse斜边
- The longest side of a right triangle, opposite the right angle.
I
- inequality不等式
- A comparison using <, >, ≤ or ≥ instead of equals.
- integer整数
- Whole numbers and their negatives: …, −2, −1, 0, 1, 2, …
- interest利息
- Money paid for using money — simple or compound.
M
- mean均值
- Sum of the data divided by the number of data points.
- median中位数
- The middle value when data is sorted in order.
- mode众数
- The value that appears most often in a data set.
N
- negative number负数
- A number less than zero, written with a minus sign.
- numerator分子
- The top number of a fraction — how many parts we have.
O
- obtuse angle钝角
- An angle between 90° and 180°.
- odd number奇数
- A whole number not divisible by 2.
P
- parallel lines平行线
- Lines in the same plane that never meet.
- perimeter周长
- The distance all the way around a shape.
- pi (π)圆周率
- Circumference ÷ diameter of any circle, about 3.14159.
- polygon多边形
- A closed flat shape with straight sides, like a hexagon.
- prime number质数
- A whole number greater than 1 with exactly two factors: 1 and itself.
- probability概率
- The chance an event happens, between 0 and 1.
- product积
- The result of multiplying numbers.
- proportion比例
- An equation saying two ratios are equal, like 1/2 = 3/6.
Q
- quotient商
- The result of division.
R
- radius半径
- The distance from the center of a circle to its edge.
- ratio比
- A comparison of two quantities by division, like 3:2.
- right angle直角
- An angle of exactly 90°.
S
- square root平方根
- A number that multiplied by itself gives the original, √9 = 3.
- statistics统计学
- The math of collecting, organizing and interpreting data.
- sum和
- The result of adding numbers.
- symmetry对称
- A shape matches itself after a flip or turn.
V
- variable变量
- A letter standing for an unknown or changeable number, like x.
- volume体积
- The amount of space inside a 3D object.