Question based on Primebox method--Ron Purewal Video

[dddanny2006]

Hey Ron

I really enjoy your videos on Vimeo.Here's a question that I did not understand.

Original question-- Source:Ron's video on Vimeo

Is mn divisible by 40? ----------------Do we have 2x2x2x5
(1)m is divisible by 10
(2)n is divisible by 4

In the video we directly overrule St1 and St2 individually.Im confused as a result.Here's my method to it.Please correct me if Im wrong.

Statement 1 --Primebox for m includes 2,5.....?????
We need two more 2's and a 5.If at all they do come,from where will they come?Will they come from the "2,5,......?"the dots that Ive bolded?Or will they come from n.St1 mentions nothing about n.

Since we may or may not get a 2x2x2x5 Statement 1 is insufficient.

Similar is the case for statement 2 as well, here we have 2,2.....??? .We need one more 2 and a 5.We are not sure whether we'll have them or not.Again the same question,if we have them where will they come from?Will they again emerge from those dots"....???" that Ive bolded,or from m in this case? Or can they be a combination from both m as well as the dots..This too is insufficient.

C is the answer.


Thanks Ron

[RonPurewal]

Looks good to me.

[dddanny2006]

Okay Ron,

I have a doubt.

When they ask us

Is mn divisible by 40---Do we have 2 2 2 5
(1)m is divisible by 40--We have a 2 2 2 5 in the Primebox

Nothing is spoken about n,all we know is that m does have a 2 2 2 5. Just because m is divisible by 40,in otherwords has a 2 2 2 5,,how can we say for sure that mn is divisible by 40?

Thanks Ron

Hey Ron

I really enjoy your videos on Vimeo.Here's a question that I did not understand.

Original question-- Source:Ron's video on Vimeo

Is mn divisible by 40? ----------------Do we have 2x2x2x5
(1)m is divisible by 10
(2)n is divisible by 4

In the video we directly overrule St1 and St2 individually.Im confused as a result.Here's my method to it.Please correct me if Im wrong.

Statement 1 --Primebox for m includes 2,5.....?????
We need two more 2's and a 5.If at all they do come,from where will they come?Will they come from the "2,5,......?"the dots that Ive bolded?Or will they come from n.St1 mentions nothing about n.

Since we may or may not get a 2x2x2x5 Statement 1 is insufficient.

Similar is the case for statement 2 as well, here we have 2,2.....??? .We need one more 2 and a 5.We are not sure whether we'll have them or not.Again the same question,if we have them where will they come from?Will they again emerge from those dots"....???" that Ive bolded,or from m in this case? Or can they be a combination from both m as well as the dots..This too is insufficient.

C is the answer.


Thanks Ron

[RonPurewal]

When you multiply two numbers together, what happens to the primes that are in them?

[dddanny2006]

It could be that n could be one,or have other prime factors.As long as we have a 2 2 2 5 that m gives us,its safe to say that mn is divisible by 40.Right?

When you multiply two numbers together, what happens to the primes that are in them?

[RonPurewal]

It could be that n could be one,or have other prime factors.As long as we have a 2 2 2 5 that m gives us,its safe to say that mn is divisible by 40.Right?

Yes sir.

When you multiply two numbers together, you're just tossing all of the primes from both of them into a big bucket. So, yeah.