Math ReviewConsumer Economics

Math Review – Section 1•Objectives:

▫Identify each position of the decimal number system

▫Write numbers or amounts in word form▫Round numbers to approximate an answer▫Round numbers

The Decimal Number System•Decimal Number System

▫Also called the Hindu-Arabic system▫Number system that uses base 10▫Based on 10 digits

A digit is a numeral

The Decimal Number System•Decimal Number System

▫A dot called a decimal point separates whole numbers from decimal numbers

▫The names of the digits to the left and right of the decimal point are called position or places

▫Commas are used to the left of the decimal point to separate each group of three digits Digits to the left form whole number parts Digits to the right of the decimal point form

the decimal part

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Word Forms•Word Forms

▫Numbers or amounts may be spelled out▫The decimal point is represented by the

word andNumbers Word Forms

3 Three

28 Twenty-eight

39.06 Thirty-nine and six hundredths

837 Eight hundred thirty-seven

4,169 Four thousand one hundred sixty-nine

72.1 Seventy-two and one tenth

283.512 Two hundred eighty-three and five hundred twelve thousandths

Word Forms•Check writing

▫Bank requires you to write the amount in both number and word forms

▫Cents are written as a fraction of a dollar 50 Cents = 50/100 Written along side the word form

Check for Understanding•Identify each numeral and decimal

position. Then write the number in word form.

1.78

567.2356

4,345.539

65,239.07548

1,234,678.98

4,798,643,087.6

Name ___________________________ Date_________________

Rounding•Approximate

▫To come near to an amount rather than give an exact number $219.95 will round up to $220 $219.05 will round down to $219.00

Rounding•Steps

1. Determine the position (place) being rounded

2. If the digit to the right of the position (place) is 5 or more, round up by 1Example: 6.8 rounds up to 7 (8 is more than 5)

3. If the digit to the right of the position is less than 5, do not round up. Drop all digits from that position to the right

Example: 6.4 rounds down to 6 (4 is less than 5)

Check for Understanding•Round each number to its nearest place

value

Name ___________________________ Date_________________

5.35 Round to the nearest tenth

0.981Round to the nearest

hundredth

0.99 Round to the nearest tenth

0.09 Round to the nearest tenth

358.8549Round to the nearest

thousandth

2976.8 Round to the nearest hundred

Math Review – Section 2•Objectives:

▫Identify terms used with addition▫Align numbers correctly for adding▫Align decimal points in addition▫Add negative numbers▫Combine addition and subtraction

Addition•Addition

▫The process of combining two or more numbers and arriving at a larger number

▫Each number is called an addend▫The solution is called the sum, total, or

amount

931+ 27 958

Addend

Addend

Sum, Total, or Amount

Addition•Align numbers correctly for adding

▫Align in columns Tens above tens, hundreds above hundreds,

etc. 8,712 256 3,421 951+ 13,340

Check for Understanding•Align the following addends properly, then

find the sum, total or amount.

Name ___________________________ Date_________________

4236,729+18,705

7160,552194+7086

8,36024,05815321,789+8,435,905

Addition•Align decimal points

▫Number of decimal places is determined by addend with the largest number of decimal places

5,146.11 56.044 10.07 694.081+ 1,237.0548 7,148.3598

Addend with largest number of decimal places

Answer has 4 decimal places

Check for Understanding•Align the following decimal addends

properly, then find the sum, total or amount.

Name ___________________________ Date_________________

3.9876567.905+197,534.032

23.4861353,987.219,420.987+4907

629.54324.058713.4321.78+8,435.90573

Adding Negative Numbers•You may be required to add a column of

negative numbers▫Add as if they were positive numbers,

placing the negative sign before the answer

47 83 23 15 168

Check for Understanding•Align the following negative addends

properly, then find the sum, total or amount.

Name ___________________________ Date_________________

321437,890

5465223,9535,620

917324052174328,031

Adding Negative Numbers•Combine addition and subtraction

1. Total the positive numbers2. Total the negative numbers3. Subtract the two

If the total of the positive numbers is larger, then the answer is positive

If the total of the negative numbers is larger, then the answer is negative

Adding Negative Numbers•Combine addition and subtraction

251388726

25 + 13+ 7 = 45

- 88 – 26 = -114

-114+45-69

Total of Positive Numbers

Total of Negative Numbers

Subtract

Solution

Check for Understanding•Align the following addends properly, then

find the sum, total or amount.

Name ___________________________ Date_________________

430815976

2,95665821,4383

7,5258,0942349271278