In a two-digit number, the ones digit is twice the tens digit. If the digits are reversed, the new number is 36 more than the original number. Find the number.

Answer 1

The number is 48. Reverse it to get 84 = 36+48

Let U = the ones digit and T = the tens digit

then U=2T

the number is 10T+U

reverse them and the number is 10U+T = 36 + 10T+ U.

or 9U-9T = 36 divide by 9

U-T =4

U=4+T

That gives 6 possibilities:

T=0, U=4

T=1, U=5

T=2, U=6

T=3, U=7

T=4, U=8

T=5, U=9

Only T=4, U=8 has U=2T, so the number is 48