Idiot\'s Guides Basic Math and Pre-Algebra

Chapter 6: Decimals 69 The decimal fractions are written to the right of the decimal point. The first position after the point i ...

70 Part 1: The World of Numbers Different Names, Same Number Decimal fractions can sometimes go by more than one name. If you wr ...

Chapter 6: Decimals 71 Powers and Scientific Notation Revisited ................................................................ ...

72 Part 1: The World of Numbers Scientific Notation for Small Numbers Writing small numbers in scientific notation is almost the ...

Chapter 6: Decimals 73 left because, for small numbers, the exponent is negative. You can add zeros if you run out of digits. Th ...

74 Part 1: The World of Numbers For example, here’s how you add 34.82 and 9.7. Align the decimal points and add a zero to 9.7. A ...

Chapter 6: Decimals 75 CHECK POINT Complete each addition or subtraction. 45.9 + 19.75 397.256 – 242.81 17,401.12 + 15,293.101 ...

76 Part 1: The World of Numbers Start from the right side and count to the left. The 2 in 62 is one digit, the 6 is a second, bu ...

Chapter 6: Decimals 77 So if that’s how you divide a decimal by a whole number, how do you divide by a decimal? You don’t. What ...

78 Part 1: The World of Numbers WORLDLY WISDOM If you’ve done your division and still have a remainder, you can add zeros to the ...

Chapter 6: Decimals 79 If you’re changing a fraction to a decimal and you find that you’ve gotten several digits in the decimal ...

80 Part 1: The World of Numbers Rational and Irrational Numbers When you met rational numbers, you might have wondered if there ...

Chapter 6: Decimals 81 MATH IN THE PAST Pi is the name given to the ratio of a circle’s circumference, the measurement around th ...

82 Part 1: The World of Numbers To do arithmetic with decimal fractions, work as though they were whole numbers, then follow th ...

CHAPTER 7 Ratios, Proportions, and Percentages In This Chapter How to compare numbers by creating ratios Using ratios to solve ...

84 Part 1: The World of Numbers If you had two lamps, one 2 feet tall and one 3 feet tall, you could say one is 1.5 times taller ...

Chapter 7: Ratios, Proportions, and Percentages 85 An extended ratio compares more than two numbers. Extended ratios are usually ...

86 Part 1: The World of Numbers CHECK POINT If the ratio of girls to boys in Math Club is 5:3, and there are 32 members of the ...

Chapter 7: Ratios, Proportions, and Percentages 87 your second ratio is big triangle to small triangle just like the first ratio ...

88 Part 1: The World of Numbers WORLDLY WISDOM When you’re cross-multiplying, don’t be in a rush to do the arithmetic, especiall ...