Video: Finding the Least Common Denominator

Scene #

Description

Narration

1

A woman is standing outside of a movie theater. On the Now showing sign is a number line. The camera zooms in on the number line. The number lines she talks about appear on the screen.

- WE ARE GOING TO FIND COMMON NUMBERS

ON DIFFERENT NUMBER LINES.

HERE'S A NUMBER LINE FOR 3s,

3, 6, 9, AND SO ON.

HERE'S A NUMBER LINE FOR 5s

5, 10, 15, AND SO ON.

WHAT'S THE FIRST NUMBER THAT'S COMMON TO BOTH NUMBER LINES?

YES, 15.

HERE IT IS FOR 3s, AND HERE IT IS FOR 5s.

- HERE'S A NEW PAIR OF NUMBER LINES.

THE FIRST IS 2s.

THE SECOND IS 8s.

YOU'RE GOING TO FIND THE FIRST NUMBER

THAT IS COMMON TO BOTH NUMBER LINES.

WHAT'S THE FIRST COMMON NUMBER?

- YES, 8.

HERE IT IS FOR 2s, AND HERE IT IS FOR 8s

2

The woman is pointing to individual numbers on the Now showing screen. The camera zooms in and the numbers appear on the screen as the woman talks.

- LET'S DO 1 WITHOUT USING THE NUMBER LINES.

HERE'S 2, AND HERE'S 5.

THE FASTEST WAY TO FIND THE FIRST COMMON NUMBER

FOR 2 AND 5 IS START COUNTING BY THE LARGEST NUMBER.

START COUNTING BY 5 AND FIND THE FIRST NUMBER

THAT YOU WOULD REACH COUNTING BY 2.

DO IT SILENTLY.

HERE'S ANOTHER PAIR OF NUMBERS: 6 AND 4.

START WITH THE LARGER NUMBER 6 AND COUNT BY 6.

FIND THE FIRST NUMBER YOU'D REACH BY COUNTING BY 4s.

- HERE'S ANOTHER PAIR OF NUMBERS.

WHICH NUMBER ARE YOU GOING TO START COUNTING BY?

- YES, 8, THE LARGER NUMBER.

WRITE THE FIRST NUMBER THAT YOU'D REACH

COUNTING BY 8 AND COUNTING BY 6.

HERE ARE 3 NUMBERS.

YOU'RE GOING TO FIND THE FIRST NUMBER

THAT WOULD BE COMMON TO ALL 3 NUMBER LINES.

WHICH NUMBER DO YOU START COUNTING BY?

- YES, 5.

YOU START COUNTING BY 5 AND FIND THE FIRST COMMON NUMBER

YOU REACH COUNTING BY 4s AND COUNTING BY 2s.

WHAT IS THE FIRST COMMON NUMBER?

- YES, 20.

HERE'S THE NUMBER LINE FOR 5s.

HERE IT IS FOR 4s.

HERE IT IS FOR 2s.