I have learned that 9 is the perfect number. If you multiply any number by nine you can check your answer by adding the numbers in the total, and they will always break down to 9.
Example 9 X 2 =18 1+8=9... 325 x 9 = 2925 2+9+2+5= 18 1+8 =9 417 X 9 =3753 3+7+5+3= 18 1+8=9 Try any number if it comes up with any number besides 9 then your first answer is incorrect.
