Multiplying whole numbers
Multiplication is a mathematical operation that indicates how many times a number is added to itself.
2 x 5 = 10 5 + 5 = 10
Multiplying two groups of 5 Adding two groups of 5
Multiplication is repeated addition. Add repeatedly (or skip-count) to multiply
2 x 5 = 10
2 x 5 = 2 + 2 + 2 + 2 + 2 = 10
Multiplicand is a number that is to be multiplied by another (the multiplier). Product is the result of multiplying two (or more) numbers, for instance, 10 is the product of 2 and 5.
Factors are the numbers that are multiplied together.
Long multiplication (traditional method)
In this method we multiply the multiplicand by each digit of the multiplier and then add up all the properly shifted results.
Step one: Multiply by ones digit to get the first partial product.
Step two: Multiply by tens digit to get the second partial product.
Step three: Multiply by hundreds digit to get the third partial product.
Step four: …
Last step: Add all partial products together to get the final product!
In this example, we multiply by the units and the tens separately.
34 x 21 = 34 x (20 + 1) = 34 x 20 + 34 x1 =680 + 34 = 714
The box method (partial products method) works by splitting each number into tens and units
Example: 34 = 30+4 and 21 = 20+1
34 x 21 = 600+80+30+4 = 714
On a separate sheet of paper, multiply and check your answers.
Word Problems – Using Whole Numbers