+,   Math Dictionary 
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A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z 
I I equals 1 in Roman numerals. 
i i is an imaginary number, defined as the square root of negative one. 
icosahedron An icosahedron is a twentysided geometric solid. 
0 identity for addition The additive identity is the number zero because zero plus any number is equal to the original number. For example, 
1 identity for multiplication The identity for multiplication (also called the multiplicative identity) is one, because a times 1 = 1 times a = a. For example, 2 times 1 = 1 times 2 = 2. 
illusion An illusion is something that tricks your eyes. 
i imaginary number An imaginary number is a number of the form bi, where i is the square root of negative one and b is a real number. 
improper fraction An improper fraction is one whose numerator is larger than the denominator (like 5/4). Improper fractions can be written as a mixed number, a number plus a fraction (5/4 = 1 1/4). 
inch An inch is a unit of measurement that is equal to onetwelfth of a foot. The symbol for inch is ". 
inequality An inequality is a mathematical expression that contains an inequality symbol. The inequality symbols are :
< less than (1<2)

infinity Infinity is a concept of endlessness. The symbol above represents infinity. 
integer The integers are the numbers ..., 3, 2, 1, 0, 1, 2, .... 
intersection An intersection is where two or more things, like roads or sets, meet or overlap. The intersection of two sets is the set of objects that belong to both of the original sets. 
inverse property of addition The inverse property of addition states that for every number a, a + (a) = 0 (zero). 
inverse property of multiplication The inverse property of multiplication states that for every nonzero number a, a times (1/a) = 1. 
irrational number An irrational number is a number that cannot be written as a fraction (like a/b, where a and b are whole numbers and b is ≠ 0). For example, the square root of 2 is an irrational number. 
isosceles triangle An isosceles triangle has two sides that are the same length and two angles that are the same. 
+,   Math Dictionary 
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A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z 
Counting  Addition  Subtraction  Multiplication  Division 
Number Line  Fractions  Decimals  Graphs  Measurement  Rounding 
Click on an underlined word for more information on that subject. If the math term you are looking for is not in the dictionary, please email us.
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