Figure 1. Locate the given place value and mark it with an arrow. Underline the digit to the right of the place value. Is the underlined digit greater than or equal to 5?
Yes: add 1 to the digit in the given place value. No: do not change the digit in the given place value Rewrite the number, deleting all digits to the right of the rounding digit. Add and Subtract Decimals To add or subtract decimals, we line up the decimal points. Determine the sign of the sum or difference. Write the numbers so the decimal points line up vertically. Use zeros as placeholders, as needed. Add or subtract the numbers as if they were whole numbers.
Then place the decimal point in the answer under the decimal points in the given numbers. Write the sum or difference with the appropriate sign. Multiply and Divide Decimals When we multiply signed decimals, first we determine the sign of the product and then multiply as if the numbers were both positive. Determine the sign of the product. Write in vertical format, lining up the numbers on the right. Multiply the numbers as if they were whole numbers, temporarily ignoring the decimal points.
Place the decimal point. The number of decimal places in the product is the sum of the number of decimal places in the factors. Write the product with the appropriate sign. Determine the sign of the quotient. Place the decimal point in the quotient above the decimal point in the dividend. Write the quotient with the appropriate sign.
Convert Decimals, Fractions, and Percents In our work, it is often necessary to change the form of a number. To convert a decimal to a proper fraction, determine the place value of the final digit. Write the fraction. To convert a percent to a decimal, move the decimal point two places to the left after removing the percent sign.
To convert a decimal to a percent, move the decimal point two places to the right and then add the percent sign. Identify Integers, Rational Numbers, Irrational Numbers, and Real Numbers We have already described numbers as counting number s , whole number s , and integers.
Its decimal form stops or repeats. Its decimal form does not stop and does not repeat. Locate Fractions and Decimals on the Number Line We now want to include fractions and decimals on the number line. Key Concepts How to round decimals.
How to add or subtract decimals. Write the sum or difference with the appropriate sign How to multiply decimals. How to multiply a decimal by a power of ten. Move the decimal point to the right the same number of places as the number of zeros in the power of Add zeros at the end of the number as needed. How to divide decimals. It is called zero, nil, nought etc. It is also a place-holder. It is first used in this sense in the number ten The 0 denotes that there is nothing in the units place, and therefore distinguishes 10 from 1.
The concept of place holder is best interpreted as there being zero 0 of the units in the place where the 0 is. For example, in there are zero hundreds. Students need to meet the number 0 before they meet the number Any real number that is not a Rational Number.
Includes all Rational Numbers, and some Irrational Numbers. They are called "Real" numbers because they are not Imaginary Numbers. If you square a real number you always get a positive, or zero, result.
The values a and b can be zero, so the set of real numbers and the set of imaginary numbers are subsets of the set of complex numbers. Symbol Description Natural Numbers The whole numbers from 1 upwards.
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