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Decimals: Reading, Writing, and Rounding. Section 4.1. Objectives. Write word names from place value names and place value names from word names Round a given decimal. Objective 1: Write word names from place value names and place value names from word names. Objective 1.
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Decimals: Reading, Writing, and Rounding Section 4.1
Objectives • Write word names from place value names and place value names from word names • Round a given decimal
Objective 1: Write word names from place value names and place value names from word names
Objective 1 • Decimal numbers (commonly called decimals) – another way of writing fractions and mixed numbers • Decimal point – separates the whole number part from the fraction part • Number of decimal places – number of digits to the right of the decimal point
Objective 1 • Place values for decimals • Same as whole numbers for the digits to the left of the decimal point • Fraction whose denominator is 10, 100, 100, etc., for digits to the right of the decimal point • Hundreds, tens, ones, tenths, hundredths, thousandths, etc. • If decimal point is not written, it is understood to follow the ones place • Expanded form
Objective 1 • To write word name • Write name of whole number that is left of decimal point • Write “and” for the decimal point • Write whole number name of number that is to right of decimal point • Write place value of digit farthest to right • If number has only zero or no number left of decimal, omit step 1 and 2
Objective 1 • To write place value name • Write whole number (the number before “and”) • Write decimal point for the word “and” • Ignore place value name, and write name for number following “and”. Insert zeros, if necessary, between decimal point and the digits following it to ensure the correct place value.
Objective 2 • Exact decimals – exact values • Approximate decimals – rounded values • Decimals are rounded using same procedures as whole numbers
Objective 2 • To round a decimal number • Draw an arrow under the given place value • If digit to right of arrow is 5, 6, 7, 8, 9, then round up • If digit to right of arrow is 1, 2, 3, 4, then digit at the arrow stays the same • Write zeros, if necessary, to right of arrow