# Transcript: Matrix Multiplication

(music plays)

Sarah stands next to a wall touch screen showing a word problem, a two-column table and a multiplication example. She is in her mid-twenties, with short straight brown hair. She wears a blue T-shirt with a print that reads "Home Work Zone" and black tights.

She says HEY,

TVO KIDS,

I'M TEACHER SARAH,

AND TODAY,

I'M GOING TO

TEACH YOU A NEW WAY

TO MULTIPLY, USING

A MATRIX.

THIS IS A

REALLY SIMPLE,

EASY WAY TO DO

MENTAL MATH.

LET'S GIVE IT

A SHOT TOGETHER.

SO FOR EXAMPLE,

I HAVE

MY MULTIPLICATION

QUESTION, WHICH IS 55

MULTIPLIED BY

EIGHT.

SO NOW I NEED TO

FIND THE PRODUCT.

IN ORDER TO USE

THIS METHOD,

THE FIRST THING

I HAVE TO DO IS

BREAK MY NUMBERS

DOWN BY USING

PLACE VALUE,

OR THINK ABOUT

THE TENS COLUMN AND

THE ONES COLUMN.

LET'S START

WITH MY 55.

IF I TAKE A LOOK

AT MY 55,

I KNOW THAT

THIS FIVE IS IN

THE TENS COLUMN,

AND THAT

THAT

REPRESENTS 50.

SO I'M GOING TO

WRITE THAT

VALUE

RIGHT HERE.

NOW I'M GOING TO

TAKE A LOOK

AT THE

ONES COLUMN.

I SEE THERE'S

A FIVE IN

THE

ONES COLUMN,

BUT THAT FIVE ONLY

REPRESENTS FIVE.

I'M GOING TO

WRITE THAT NUMBER

RIGHT HERE.

NOW I CAN MOVE ON

TO MY NEXT NUMBER.

EIGHT.

THIS ONE'S

EASY.

EIGHT IS ALREADY

IN THE ONES PLACE,

SO I SIMPLY WRITE MY

NUMBER DOWN HERE.

THE NEXT THING

THAT I HAVE TO DO

IS I HAVE TO MULTIPLY

THE NUMBERS

TOGETHER AND

WRITE MY PRODUCT

IN THE

COLUMN.

SO 50 MULTIPLIED

BY EIGHT.

I KNOW THAT EIGHT

TIMES FIVE IS 40,

AND WHEN I'M

MULTIPLYING BY TENS,

I CAN ADD

MY ZERO.

SO IF EIGHT

TIMES FIVE IS 40,

THEN EIGHT TIMES

50 IS 400.

WRITE THAT

NUMBER HERE.

PERFECT.

NOW I DO THE SAME

THING FOR

MY

NEXT COLUMN.

I MULTIPLY FIVE

BY EIGHT,

WHICH

IS 40.

WRITE IT DOWN

IN HERE,

AND I AM

ALMOST DONE.

THE NEXT THING THAT

I HAVE TO DO

IS SUM UP, OR

ADD UP ALL OF MY

NUMBERS IN MY

COLUMN.

SO I HAVE

400 PLUS 40,

She writes the steps mentioned in purple and continues AND THAT GIVES

ME AN ANSWER,

OR A

PRODUCT OF 440.

SO 55 MULTIPLIED BY

EIGHT IS 440.

THERE YOU

HAVE IT, TVO KIDS,

A NEW WAY TO DO

MENTAL MATH,

USING

A MATRIX.

SEE YOU NEXT

TIME!

Sarah stands next to a wall touch screen showing a word problem, a two-column table and a multiplication example. She is in her mid-twenties, with short straight brown hair. She wears a blue T-shirt with a print that reads "Home Work Zone" and black tights.

She says HEY,

TVO KIDS,

I'M TEACHER SARAH,

AND TODAY,

I'M GOING TO

TEACH YOU A NEW WAY

TO MULTIPLY, USING

A MATRIX.

THIS IS A

REALLY SIMPLE,

EASY WAY TO DO

MENTAL MATH.

LET'S GIVE IT

A SHOT TOGETHER.

SO FOR EXAMPLE,

I HAVE

MY MULTIPLICATION

QUESTION, WHICH IS 55

MULTIPLIED BY

EIGHT.

SO NOW I NEED TO

FIND THE PRODUCT.

IN ORDER TO USE

THIS METHOD,

THE FIRST THING

I HAVE TO DO IS

BREAK MY NUMBERS

DOWN BY USING

PLACE VALUE,

OR THINK ABOUT

THE TENS COLUMN AND

THE ONES COLUMN.

LET'S START

WITH MY 55.

IF I TAKE A LOOK

AT MY 55,

I KNOW THAT

THIS FIVE IS IN

THE TENS COLUMN,

AND THAT

THAT

REPRESENTS 50.

SO I'M GOING TO

WRITE THAT

VALUE

RIGHT HERE.

NOW I'M GOING TO

TAKE A LOOK

AT THE

ONES COLUMN.

I SEE THERE'S

A FIVE IN

THE

ONES COLUMN,

BUT THAT FIVE ONLY

REPRESENTS FIVE.

I'M GOING TO

WRITE THAT NUMBER

RIGHT HERE.

NOW I CAN MOVE ON

TO MY NEXT NUMBER.

EIGHT.

THIS ONE'S

EASY.

EIGHT IS ALREADY

IN THE ONES PLACE,

SO I SIMPLY WRITE MY

NUMBER DOWN HERE.

THE NEXT THING

THAT I HAVE TO DO

IS I HAVE TO MULTIPLY

THE NUMBERS

TOGETHER AND

WRITE MY PRODUCT

IN THE

COLUMN.

SO 50 MULTIPLIED

BY EIGHT.

I KNOW THAT EIGHT

TIMES FIVE IS 40,

AND WHEN I'M

MULTIPLYING BY TENS,

I CAN ADD

MY ZERO.

SO IF EIGHT

TIMES FIVE IS 40,

THEN EIGHT TIMES

50 IS 400.

WRITE THAT

NUMBER HERE.

PERFECT.

NOW I DO THE SAME

THING FOR

MY

NEXT COLUMN.

I MULTIPLY FIVE

BY EIGHT,

WHICH

IS 40.

WRITE IT DOWN

IN HERE,

AND I AM

ALMOST DONE.

THE NEXT THING THAT

I HAVE TO DO

IS SUM UP, OR

ADD UP ALL OF MY

NUMBERS IN MY

COLUMN.

SO I HAVE

400 PLUS 40,

She writes the steps mentioned in purple and continues AND THAT GIVES

ME AN ANSWER,

OR A

PRODUCT OF 440.

SO 55 MULTIPLIED BY

EIGHT IS 440.

THERE YOU

HAVE IT, TVO KIDS,

A NEW WAY TO DO

MENTAL MATH,

USING

A MATRIX.

SEE YOU NEXT

TIME!

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