# Key Concepts

### 1.1 Introduction to Whole Numbers

Figure 1.16

• Name a whole number in words.
1. Step 1. Starting at the digit on the left, name the number in each period, followed by the period name. Do not include the period name for the ones.
2. Step 2. Use commas in the number to separate the periods.
• Use place value to write a whole number.
1. Step 1. Identify the words that indicate periods. (Remember the ones period is never named.)
2. Step 2. Draw three blanks to indicate the number of places needed in each period.
3. Step 3. Name the number in each period and place the digits in the correct place value position.
• Round a whole number to a specific place value.
1. Step 1. Locate the given place value. All digits to the left of that place value do not change unless the digit immediately to the left is 9, in which case it may. (See Step 3.).
2. Step 2. Underline the digit to the right of the given place value.
3. Step 3. Determine if this digit is greater than or equal to 5. If yes—add 1 to the digit in the given place value. If that digit is 9, replace it with 0 and add 1 to the digit immediately to its left. If that digit is also a 9, repeat. If no—do not change the digit in the given place value.
4. Step 4. Replace all digits to the right of the given place value with zeros.