Math Dictionary for Kids

The #1 Guide for Helping Kids With Math

Theresa R. Fitzgerald

• Publisher: Routledge
• Year: 2021
• ISBN:
  9781000494402
• Edition: 5
• Topic: Education
• Subtopic: Education General

Equipped with the #1 guide to help kids with math homework, children will be able to quickly find the definitions and illustrated examples that will enable them to solve many of the math challenges they face. Covering everything from "addend" to "zero, " the fifth edition of the best-selling Math Dictionary for Kids gives students in grades 4-9 more than 400 definitions, full-color illustrations, and examples that can help them solve math problems.This handbook includes illustrated, concise explanations of the most common terms used in general math classes, categorized by subjects that include measurement, algebra, geometry, fractions and decimals, statistics and probability, and problem solving. This edition also discusses how students can use manipulatives and basic math tools to improve their understanding and includes handy measurement conversion tables. Each term has a concise definition and an example or illustration. Perfect for both kids and their parents looking to help them with math homework!

QUICK REFERENCE GUIDES

DOI: 10.4324/9781003236443-9

QUICK REFERENCE GUIDE: DECIMALS

DOI: 10.4324/9781003236443-10

Adding Decimals

1. Line up the decimal points so that the place value is in line.
2. Add as normal. Zeros can be added after the decimal point in order to make adding easier, and it won’t change the answer.
3. Bring the decimal point straight down into the answer.

$\begin{array}{r}\hfill 5+.34+2.738=\\ \hfill 5.000\\ \hfill .340\\ \hfill \frac{+2.738}{8.078}\end{array}$

$\begin{array}{r}\hfill .83+4.2=\\ \hfill .83\\ \hfill \frac{+4.20}{5.03}\end{array}$

$\begin{array}{r}\hfill 9+6+.34=\\ \hfill .90\\ \hfill 6.00\\ \hfill \frac{+.34}{7.24}\end{array}$

Comparing Decimals

To determine which decimal is larger or smaller, place value must be compared.

1. Line up the decimal points.
2. Compare tenths, then hundredths, and then thousandths.

1. Line up decimal points. ${}_{0.324}^{0.56}$
2. Look at place value: 5 tenths is larger than 3 tenths, so 0.56 is larger than 0.324.

Converting Decimals

✪ Decimal to Fraction

To change a decimal to a fraction, use place value.

1. Decide whether the decimal represents tenths, hundredths, thousandths, etc.
2. Write the numerical part of the decimal over the appropriate power of 10—over 10 if the decimal was in the tenths place, over 100 if the decimal was in the hundredths place, and so on.
3. Reduce the fraction.

Example:

.05 is 5 hundredths.

$$\frac{5}{100}\frac{5}{100}÷\frac{5}{5}=\frac{1}{20}$$

✪ Decimal to Percent

To change a decimal to a percent, move the decimal point.

1. Move the decimal point two places to the right.
2. Add a percent sign (%).
3. Add zeros for placeholders if necessary.

Examples:

.72 = 72%	.8 = 80%
.523 = 52.3%	.09 = 9%

✪ Fraction to Decimal

To find the decimal for a fraction: ⅜

1. Divide the numerator by the denominator.
   $$8\overline{)3}$$
2. Add a decimal point and zeros to the dividend. Bring the decimal point straight up to the quotient.
   $$8\overline{)3.00}$$
3. Divide as normal; write the answer with the decimal point.

   

Dividing Decimals

1. Write the problem as normal.
2. Bring the decimal point straight up.
3. Divide as normal.

Multiplying Decimals

1. Write and solve the problem as normal.
2. Count the total number of places after each decimal in the numbers being multiplied.
3. Position the decimal the same number of places in the answer.

$$\begin{array}{r}\hfill 3.15\\ \hfill \frac{\times 2.7}{2205}\\ \hfill \frac{+6300}{8.505}\end{array}$$

Subtracting Decimals

1. Line up the decimal points so that the place value is in line.
2. Subtract as normal. Zeros can be added after the decimal point in order to make subtracting easier, and it won’t change the answer.
3. Bring the decimal point straight down into the answer.

$$\begin{array}{c}6\stackrel{7}{\cancel{8}}.\stackrel{2}{\cancel{3}}\stackrel{10}{\cancel{0}}\\ \frac{-4.69}{...}\end{array}$$