Multiplication By Chunking
Published on Nov 19, 2015
No Description
MORE DECKS TO EXPLORE
PRESENTATION OUTLINE
18 X 14
FIND THE PRODUCT
Multiplication can be thought of as repeated addition.
In this problem, you might think of 18 groups of 14 being added together one at a time.
In this problem, you might think of 18 groups of 14 being added together one at a time.
Photo by liquidnight
REPEATED ADDITION
18 GROUPS OF 14
I bet she's thinking about using that calculator.
Even if she decides to use her calculator, she'll have to keep up with each addition so that she performs exactly 18 of them.
Photo by Steven Leith
PENCILS PLEASE
NO CALCULATOR
NO CALCULATORS!!!
Does this mean that we'll have to keep adding 14 until we've added all 18 addends?
By the way, I've forgotten why we are multiplying 18 times 14. We'll get back to that later.
Photo by Bilal Lashari
14+14+14+14+...
NOT!
Even with the calculator, we'd have to be sure to enter 14 exactly 18 times.
Photo by angelsk
LET'S CHUNK.
Let's gather larger groups of 14 together so we don't have to perform so many additions.
Let's CHUNK!
Photo by Leo Reynolds
GROUP 10CHUNKS OF 14
THAT'S 140
I like 10 because it is a friendly number to add, subtract, multiply, or divide by.
Let's add 10 chunks of 14 together.
Let's add 10 chunks of 14 together.
Photo by onezilla
ADD 5 MORE CHUNKS
THAT'S 70 MORE (140+70+?)
Five is another friendly number in multiplication. I know my multiples of five.
And five is half of ten.
And five is half of ten.
Photo by Leo Reynolds
ADD 2 CHUNKS
THAT'S 28 MORE (140+70+28+?)
Those twos are also friendly numbers. Multiplying by two is the same as doubling a number.
Photo by Leo Reynolds
18 X 14 = 252
THE PRODUCT IS 252.
We're done! Did anybody do this a different way?
Photo by Sean MacEntee
