Associative property : An operation * has the associative property if we have $(a*b)*c=a*(b*c)$ for all $a,b,c.$

Associative property of multiplication : The associative property of multiplication says that the product of three numbers $a,b,c$ does not depend on the order in which the product is calculated: $(a\cdot b)\cdot c=a\cdot (b\cdot c).$

Parenthesis : Parenthesis or brackets are used to clarify the order of operations in an expression. Within an expression terms in parenthesis are supposed to be calculated first. For example $2\cdot(3+4)=2\cdot 7=14$ but $2\cdot 3+4=6+4=10.$

Hour : A unit for measuring time equal to 60 minutes.

Multiplication : Multiplication is the mathematical operation that is a shorthand for adding the same amount several times. For example $3\cdot 4=4+4+4=12.$

Number : A number $x$ is a mathematical symbol representing a quantity.

Least common multiple : The least common multiple of two numbers is a number that is a multiple of both numbers such that there is no smaller number that is also a multiple of both numbers. For example the least common multiple of 4 and 6 is 12.

Multiple : A multiple of a number $x$ is any of the numbers $1x,2x,3x,4x,\ldots.$ For example the multiples of 7 include 7, 14, 21 and 70.

Number : A number $x$ is a mathematical symbol representing a quantity.