PRESENTATION 1 Whole Numbers

PLACE VALUE The value of any digit depends on its place value Place value is based on multiples of 10 as follows: UNITS TENS HUNDREDSTHOUSANDS TEN THOUSANDS HUNDRED THOUSANDS MILLIONS 2, 6 7 8, 9 3 2

ESTIMATING Used when an exact mathematical answer is not required A rough calculation is called estimating or approximating Mistakes can often be avoided when estimating is done before the actual calculation When estimating, exact values are rounded

ROUNDING Used to make estimates Rounding Rules: o Determine place value to which the number is to be rounded o Look at the digit immediately to its right  If the digit to the right is less than 5, replace that digit and all following digits with zeros  If the digit to the right is 5 or more, add 1 to the digit in the place to which you are rounding. Replace all following digits with zeros

ROUNDING EXAMPLES Round 612 to the nearest hundred Since 1 is less than 5, 6 remains unchanged Answer: 600 Round 175,890 to the nearest ten thousand 7 is in the ten thousands place value, so look at 5. Since 5 is greater than or equal to 5, change 7 to 8 and replace 5, 8, and 9 with zeros Answer: 180,000

ADDITION OF WHOLE NUMBERS The result of adding numbers is called the sum The plus sign (+) indicates addition Numbers can be added in any order

PROCEDURE FOR ADDING WHOLE NUMBERS Example: Add Align numbers to be added as shown; line up digits that hold the same place value Add digits holding the same place value, starting on the right: = 12 Write 2 in the units place value and carry the one

PROCEDURE FOR ADDING WHOLE NUMBERS Continue adding from right to left Therefore, = 1,382

SUBTRACTION OF WHOLE NUMBERS Subtraction is the operation which determines the difference between two quantities It is the inverse or opposite of addition The minus sign (–) indicates subtraction

PROCEDURE FOR SUBTRACTING WHOLE NUMBERS Example: Subtract 917 – 523 Align digits that hold the same place value Start at the right and work left: 7 – 3 = 4

PROCEDURE FOR SUBTRACTING WHOLE NUMBERS Since 2 cannot be subtracted from 1, you need to borrow from 9 (making it 8) and add 10 to 1 (making it 11) Now, 11 – 2 = 9; 8 – 5 = 3 Therefore, 917 – 523 = 394

MULTIPLICATION OF WHOLE NUMBERS Multiplication is a short method of adding equal amounts There are many occupational uses of multiplication The times sign (×) is used to indicate multiplication

PROCEDURE FOR MULTIPLICATION Example: Multiply 386 × 7 Align the digits on the right First, multiply 7 by the units of the multiplicand: 7 ×6 = 42 Write 2 in the units position of the answer

PROCEDURE FOR MULTIPLICATION Multiply the 7 by the tens of the multiplicand: 7 × 8 = 56 Add the 4 tens from the product of the units: = 60 Write the 0 in the tens position of the answer

PROCEDURE FOR MULTIPLICATION Multiply the 7 by the hundreds of the multiplicand: 7 × 3 = 21 Add the 6 hundreds from the product of the tens: = 27 Write the 7 in the hundreds position and the 2 in the thousands position Therefore, 386 × 7 = 2,702

DIVISION OF WHOLE NUMBERS In division, the number to be divided is called the dividend The number by which the dividend is divided is called the divisor The result is the quotient A difference left over is called the remainder

DIVISION OF WHOLE NUMBERS Division is the inverse, or opposite, of multiplication Division is the short method of subtraction The symbol for division is ÷ The long division symbol is Division can also be expressed in fraction form such as 20 99

DIVISION WITH ZERO Zero divided by a number equals zero o For example: 0 ÷ 5 = 0 Dividing by zero is impossible; it is undefined o For example: 5 ÷ 0 is not possible

PROCEDURE FOR DIVISION Example: Divide 4,505 ÷ 6 o Write division problem with divisor outside long division symbol and dividend within symbol o Since 6 does not go into 4, divide 6 into  6 = 7; write 7 above the first 5 in number 4505 as shown o Multiply: 7 × 6 = 42; write this under 45 o Subtract: 45 – 42 = 3

PROCEDURE FOR DIVISION o Bring down the 0 o Divide: 30  6 = 5; write the 5 above the 0 o Multiply: 5 × 6 = 30; write this under 30 o Subtract: 30 – 30 = 0 o Since 6 cannot divide into 5, write 0 in the answer above the 5. Subtract 0 from 5 and 5 is the remainder o Therefore 4505  6 = 750 r5

ORDER OF OPERATIONS All arithmetic expressions must be simplified using the following order of operations: 1.Parentheses 2.Raise to a power or find a root 3.Multiplication and division from left to right 4.Addition and subtraction from left to right

ORDER OF OPERATIONS Example: Evaluate (15 + 6) × 3 – 28 ÷ 7 21 × 3 – 28 ÷ 7 63 – 4 63 – 4 = 59 Therefore: (15 + 6) × 3 – 28 ÷ 7 = 59  Do the operation in parentheses first ( = 21)  Multiply and divide next (21 ×3 = 63) and (28 ÷ 7 = 4)  Subtract last

PRACTICAL PROBLEMS A 5-floor apartment building has 8 electrical circuits per apartment. There are 6 apartments per floor. How many electrical circuits are there in the building?

PRACTICAL PROBLEMS Multiply the number of apartments per floor times the number of electrical outlets Multiply the number of floors times the number of outlets per floor obtained in the previous step There are 240 outlets in the building