Dividing by 14

Tuesday, January 12, 2010

Sara Heikali builds on her divisibility test for seven:

How can you know if a number with three or more digits 
is divisible by the number fourteen?

Check if the last digit of the original number is odd or 
even. If the number is odd, then the number is not 
divisible by fourteen. If the number is even, then apply 
the divisibility rule for seven. 

(Keep in mind, the odd and even test is to see if the number 
is divisible by two.) If the original even number is 
divisible by seven, then it is also divisible by fourteen. 
If the original even number is not divisible by seven, it 
is not divisible by fourteen.