4th Grade Math Concepts

Decimal notation for fractions

Ray
A ray has one endpoint where it starts and it extends forever on the other side.

Add mixed numbers

Comparing fractions

Read whole numbers

Which number can be read as six thousand, four hundred eighty-seven?

    A. 64087         B.    6087          

    C. 6487          D.     8764

Proper fraction
Numerator is smaller than denominator
Improper fraction
Numerator is bigger than denominator.

Right triangle
A right triangle has one right angle.

Benchmark fractions in 4th grade math
Fractions that are used frequently to do estimation.

Congruent shapes
Shapes are congruent when they have the same shape and size.

Common denominator
Multiples of 3 are 3, 6, 9, 12, 15, ...
Multiples of 4 are 4, 8, 12,16, ...
Common denominator is least common multiple or 12.

Line of symmetry

Protractor
A geometric tool used
to draw and measure angles

Arc
An arc is a part of a circle. The arc is shown in orange.

Algorithm for multiplication

Measure of an angle
The angle on the right measures 150 degrees

150 degrees

Tenth and hundredth
Tenth: one of the equal parts when a whole is divided into 10 equal parts.
Hundredth: one of the equal parts when a whole is divided into 100 equal parts.

Hundredths
The hundredths place is shown in red. The 9 means that 9 parts are colored out of 100.

8.29

Intersecting lines

Comparing decimals

Put the following decimal in order from greatest to least.
4.23    4.24    4.2    4.30    4.19

Answer:
4.30    4.24   4.23    4.20   4.19

Mixed number
A mixed number has 2 parts. First it has a whole number that is 2. Second, it has a fraction that is 4/5.

Formulas
Area and perimeter of a rectangle

Area  = length x width

Perimeter = 2 x length + 2 x width

Circle
In a circle, you can put points anywhere on the purple arc. These points will be at the same distance from the fixed black point called center.

Tenths
The tenths place is shown in red. The 2 means that 2 parts are colored out of 10.

8.29

Composite number
A number with more
than 2 factors. Factors
of 8 are 1, 2, 4, and 8.
8 is a composite number
since it has 4 factors
or 4 numbers than
can divide it evenly.

12, 9 and 8 are composite numbers.         

Factor pairs
A factor pair refers to
a set of two numbers
when multiplied will
yield a specific product.

Factor pairs of 12
are (1,12), (2, 6),
and (3, 4)

Obtuse angle
An angle bigger than 90 degrees

Decimal

10.50    5.25   61.0    0.40   .333

Number line
A straight line on which we put 0 and counting numbers.

Reasonableness
There is no need to
do the math. Instead
use estimation to
eliminate answers that
are unreasonable.
50 times 30 = 1500,
therefore, the answer is 1551

What is the product
of 47 times 32?

A. 4514      B. 1551

C. 2947       D. 8114

Multiplicative comparison
Peter has 5 times 4 = 20. Together they have 20 + 4 = 24

John has 4 tennis ball.
Peter has 5 times as many tennis ball as John.
How many tennis ball do they have together?

Perimeter

Perimeter = 2 x length + 2 x width
                  =  2 x 6 + 2 x 2
                  =  12 + 4
                  = 16

Area          =  6 x 2 = 12

Solve an equation

   What is the value
   of b in the equation
   below?
   5 + b = 12
   Since 5 + 7 = 12,
   b = 7

1 ounce

A slice of bread

A CD without the case

2 or 3 strawberries depends on the size

Pattern:
What is the next
number in the list?

12      15      18

Decompose a fraction

3/5 = 1/5 + 1/5 + 1/5

Example of prime numbers
A prime number is a number
that has only 2 factors, 1
and the number itself.
7 is a prime number because
only 1 and 7 can be
multiplied to get 7

5, 7, and 13

Decimal point
The decimal point is the dot (.) separating the whole number from the fraction in the decimal notation.

Equivalent fractions

Order of operations

3 + (2 + 4) x 5

Do parenthesis

3 + 8 x 5

Do multiplication

3 + 40

Add

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