Decimal Number Concepts – Basic College Mathematics for Teachers

Reference: K. Elayn Martin-Gay – Page 1    Definition:  Decimal

 

Read Decimal Numbers

 

Change Words to Numerals

 

Eight Tenths  =  .8

 

Thirty-Four Hundredths  =  .34

 

Nineteen Thousandths  =  .019

 

 

Write Decimal Numbers

 

Change Numerals to Words

 

.3  =  Three Tenths

 

.59  =  Firty-nine Hundredths

 

.008  =  Eight Thousands

 

 

Place Value of Decimal Numbers

 

Position of a Decimal Numeral has Value

 

Tenths      Hundredths 

 

Thousandths      TenThousandths

 

HundredThousandths

Rounding Off Decimal Numbers

 

If  N<5 Rd. Dn    If N=5 Rd. Up   If  N>5 Rd.Up

Round each Decimal to Hundredths

 

.342  Rd to Hths  = .34

 

.345  Rd to Hths  = .35

 

.347  Rd to Hths  = .36

Addition of Decimal Numbers

 

Line Up Decimals   or

Find a Common Denominator

 

.3  +  .45  =  .75

 

.67  +  .02  =  .69

 

Decimals are special Fractions

with Denominators of 10, 100, etc…

 

Subtraction of Decimal Numbers

 

Line Up Decimals  or

Find a Common Denominator

 

.67  -  .5  =  .17

 

.8  -  .03  =  .77

 

Decimals are special Fractions

with Denominators of 10, 100, etc…

Multiplication of Decimal Numbers

 

Multiply Numbers then determine

numbers behind decimals   Rt = Lt

 

.3  x  .05  =  .015

 

.02  x .03  =  .0006 

 

Decimal Places  Rt  =  Decimal Places Lt.

Division of Decimal Numbers

 

Divide Decimals but first move

decimal point on  outside & inside

 

.15  /  .5  =  .3

                     ____                    ___

.5  |  .15      =>      5  | 1.5

 

Decimal Moves Rt  =  Decimal Moves Rt

Thomas Love            Malone College          2006/2008

Decimal Number Concepts – Basic College Mathematics for Teachers

Reference: K. Elayn Martin-Gay – Page 2    Definition:  Decimal

 

Fractions to Decimals

 

Divide Denominator into Numerator

 

3 / 4 =  .75

4 ) 3.00

 

4 / 5 = .8

5 )  4.00

 

Decimals to Fractions

 

Decimals are special Fractions with

Denominators of 10, 100, 1000, etc…

 

.3  =  3  / 10

 

.45 = 45 / 100

 

 

 

Terminating Decimals

 

Decimals that stop or do not repeat!

 

.6

 

.75

 

.009

 

Repeating Decimals

 

Decimals that repeat over & over!

 

.777777…

 

.1666666…

 

.833333…

 

Equivalent or Equal Decimals

Compare:  <  =  >

 

(8/100)       .08 < .75       (75/100)

 

(3/10)     .3  =  .3     (3/10)

 

(60/100)      .6  >  .09      (9/100)

 

Change to Fractions & Check as Fractions!

 

Equivalent or Equal Decimals

Compare:  <  =  >

 

(  )       .09  __  .75       (   )

 

(3/10)     .1  __  .1     (3/10)

 

(   )      .4  __  .07      (   )

 

Change to Fractions & Check as Fractions!

Order Decimals:  Hi to Lo

 

Given:     .3     .09     .75

 

Order from Hi to Lo

 

.75,   .3   .09

 

Order from Lo to Hi

 

.09,   .3,   .75

 

Order Decimals:  Hi to Lo

 

Given:     .9     .07     .45

 

Order from Hi to Lo

 

____    ____    ____

 

Order from Lo to Hi

 

____    ____    ____

Thomas Love            Malone College          2006/2008