Question

Using the 9 digits, 1, 2, 3, 4, 5, 6,7, 8 and 9 you can arrange four different digits to form a four-digit number that is NOT divisible by 7. The digits 1238 cannot be arranged to create a four-digit number that is divisible by 7. The digits 1389 also cannot be arranged to form a four-digit number that is divisible by 7. Find one additional set (not 1238 or 1389) of four different digits that is not divisible by 7. Provide the digits to form the smallest four digit value.

Please explain.
Double Thanks to the person who helps me with this one.

Answer 1

easy. if you add or subtract 7, or a multiple of 7 to those number, they will not be divisible by 7.

1238-n*7

or 1238+n7. let n=1 ++++ 1245 not divisible by 7

Answer 2

1**** Enter 2 missing digits at index 4 from end
_ _
25