Multiplying Numbers
Properties and Facts of Multiplication
Multiplication algorithm: Please review multiplication facts and the
multiplication algorithm.
Vocabulary: The product of two numbers a and b is aâ€¢b. The â€œaâ€ and â€œbâ€
are called factors. The product may be written â€œabâ€ (omit the dot
between the letters) if the at least one of the factors is a variable.
English Words 
Math Symbols 
The product of 2 and 5

2Â·5 
The product of 2 and y

2Â·y 
The product m and n

mÂ·n 
The product of x and 2

xÂ·2 
The product of p and q

pÂ·q 
Properties of multiplication:
Multiplication property of zero: If a is any number, then
aâ€¢0 = 0â€¢a = 0
Multiplication property of one: If a is any number, then
aâ€¢1= 1â€¢a = a
Commutative property of multiplication: If a and b are any
numbers, then
aâ€¢b = b â€¢a
Associative property of multiplication: If a, b and c are any
numbers, then
a (bc) = (ab)c
Solving equations by inspection:
Example:
Solve by inspection.
5n = 25
n = 5 (guess the solution)
Multiplying by powers of ten:
To multiply by a power of ten, count
the number of zeros on the power of ten and place that many
zeros on the end of the other factor to get the answer.
Example:
100 â€¢27 = 2700
To multiply by a number that ends in zeros:
1. Drop the zeros.
2. Multiply the two remaining numbers.
3. Place the zeros at the end of the product.
Example:
2700 â€¢3 = 8100
