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Math Review. Consumer 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
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Math Review Consumer 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
Word Forms • Word Forms • Numbers or amounts may be spelled out • The decimal point is represented by the word and
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 Name ___________________________ Date_________________ • Identify each numeral and decimal position. Then write the number in word form.
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 • Determine the position (place) being rounded • 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) • 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 Name ___________________________ Date_________________ • Round each number to its nearest place value
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 Name ___________________________ Date_________________ • Align the following addends properly, then find the sum, total or amount. 8,360 24,058 15 321,789 +8,435,905 423 6,729 +18,705 71 60,552 194 +7086
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 Name ___________________________ Date_________________ • Align the following decimal addends properly, then find the sum, total or amount. 23.48613 53,987.2 19,420.987 +4907 629.543 24.0587 13.4 321.78 +8,435.90573 3.9876 567.905 +197,534.032
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 Name ___________________________ Date_________________ • Align the following negative addends properly, then find the sum, total or amount. 54 652 23,953 5,620 917 3240 5 2174 328,031 321 43 7,890
Adding Negative Numbers • Combine addition and subtraction • Total the positive numbers • Total the negative numbers • 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 25 13 88 7 26 25 + 13+ 7 = 45 Total of Positive Numbers - 88 – 26 = -114 Total of Negative Numbers -114 +45 -69 Subtract Solution
Check for Understanding Name ___________________________ Date_________________ • Align the following addends properly, then find the sum, total or amount. 2,956 658 21,438 3 7,525 8,094 2349 27 1278 430 815 976