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The Number System Videos 5 videos

ACT Aspire Math: Finding the Prime Factorization of 120
4 Views

Which of the following is the prime factorization of 120?

ACT Aspire Math: Ordering Numbers from Least to Greatest
7 Views

Which of the following lists of numbers is ordered from least on the left to greatest on the right?

ACT Aspire Math: Knowing (and Using) the Rules of Divisibility
13 Views

Place one of the following numbers into the ones digit of the number 428, while moving the other digits so that the 4 is in the position of the tho...

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ACT Aspire Math: Knowing (and Using) the Rules of Divisibility 13 Views


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Description:

Place one of the following numbers into the ones digit of the number 428, while moving the other digits so that the 4 is in the position of the thousands digit. What ones digit would make the number 428 divisible by 6 and 9?


Transcript

00:03

Okay Aspiring math people moving on another drill for you

00:07

Place one of the following numbers into the ones digit

00:10

of the number of four Twenty eight while moving the

00:12

other digits so that the four is in the position

00:16

of the thousands digit What one's digit would make the

00:19

number for twenty eight divisible by six and by nine

00:27

Well the problem asked us to shift all digits to

00:30

the left and then tack on one more number to

00:32

the end But which number gets to join the group

00:35

here Well we can't just let any old number join

00:37

the club There are standards to solve this problem We

00:40

need to divide and conquer kind of there's division involved

00:43

anyway at least conquering that's So think of visibility rules

00:48

How does that work How do they work to be

00:50

divisible by six evenly a number must be divisible by

00:54

two and three and even number is divisible by two

00:58

duck and a number is divisible by three If the

01:01

digits add up to a multiple of three what we

01:04

mean by that is like four plus two plus a

01:07

That's fourteen is that divisible by three so much and

01:11

the rule for visibility by nine is similar If the

01:13

digits add up to a multiple of nine like they

01:17

some toe eighteen or twenty seven or thirty six like

01:20

that then it's all good We're also particularly fund of

01:23

this helpful little rule Nine is a multiple of three

01:25

So if a number is divisible by nine then of

01:28

course it must be divisible by three as well In

01:30

other words there's no need to check the rules for

01:33

both three and nine So if you have a niner

01:35

there the three work In short our number needs to

01:38

be divisible by both six and nine In other words

01:40

it needs to be even like in a c t

01:44

And the digits need to add up to a multiple

01:47

of nine Well the on ly answer that satisfies both

01:50

is four So uh that's c right there It gives

01:54

us four thousand two hundred eighty for if we adam

01:57

up for post to hiss six plus aids for eighteen

02:00

plus four there is eighteen eighteen of his wine nine

02:04

and then by definition by three as well So that's

02:07

it That's the answer It's see you'd stick up for

02:10

there in the thousands place and be done with this 00:02:12.578 --> [endTime] thing

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