Given a number in base 10, is there a trick for determining if it is divisible by 7?

[moreDealsThanDS]

Given a number in base 10, is there a trick for determining if it is divisible by 7?

 

take out a calculater and divide by 7 =)

 

[ndee]

Originally posted by: OmegaNauce
take out a calculater and divide by 7 =)

 

[minendo]

Members of OT already did one homework problem for you. Try and do some by yourself.

 

[moreDealsThanDS]

Originally posted by: minendo
Members of OT already did one homework problem for you. Try and do some by yourself.

Easy tiger.

 

[Doodoo]

Take the last digit...double it...subtract it from the number....if the result is divisible by 7...then the original number is....keep doubling and subtracting as needed...

 

[flood]

Originally posted by: Doodoo
Take the last digit...double it...subtract it from the number....if the result is divisible by 7...then the original number is....keep doubling and subtracting as needed...

doesnt work
maybe youre thinking of this method

 

[Doodoo]

Yeah i think thas the one i was thinkin of....i remember it from a video i saw in math class like 10 yrs ago. It was the video with that one math wiz that would do crazy calculations in his head......

 

[bonk102]

Originally posted by: ndee

Originally posted by: OmegaNauce
take out a calculater and divide by 7 =)