text: logic buffs are you ready? what is the only two digit number (i.e., a number between 10 and 99 inclusive) with the following property?   if you add its digits together and multiply the answer by 6, you recover the original number. t  the tens digit u  the units digit   6(t+u)=10t+u 5u=4t 5/4u = t   now since t an u must be whole number digits, u must be a multiple 4, like 4 or 8. if u=4 then t=5/4(4)=5 and the number would be 54. let's check  6(5+4)=6(9)=54    ok  let's try u=8 (5/4)(8)= 10 which is supposed to  be t but 10 is not a digit   so 54 is the only answer