## Key Concepts

- The counting numbers start with 1 and continue: [latex]1,2,3,4,5\dots[/latex].
- The whole numbers are the counting numbers and zero: [latex]0,1,2,3,4,5\ldots[/latex].
- When rounding numbers, look to the digit to the right of the place value to which the number should be rounded. If it is 5 or greater, increase the digit in the place value to which you are rounding by one and replace the position to the right with a zero. If 4 or less, do not change the place value to which you are rounding but do replace the position to the right with a zero.

## Key Equations

- Identity property of addition: [latex]a+0=a[/latex].
- Commutative property of addition: [latex]a+b=b+a[/latex].
- Identity property of multiplication: [latex]a\cdot 1=a[/latex].
- Commutative property of multiplication: [latex]a\cdot b=b\cdot a[/latex].
- Multiplication property of zero: [latex]a\cdot 0=0[/latex].
- Division properties of one: [latex]a\div a=1[/latex] and [latex]a\div 1=a[/latex].
- Division properties of zero: [latex]0\div a=0[/latex] and [latex]a\div 0=\text{undefined}[/latex]..

## Glossary

**difference**- the result of subtracting
**product**- the result of multiplying
**quotient**- the result of dividing
**rounding**- to approximate the value of a number to a particular place value
**sum**- the result of adding