2012 · Q1
A number consists of two digits. The sum of the digits is 10. On reversing the digits of the number, the number decreases by 36. What is the product of the two digits?
Elementary MathematicsNumber System
- A21
- B24
- C36
- D42
Explanation
Let the digits be a and b with a+b=10. Reversing decreases the number by 36, so 9(a-b)=36, giving a-b=4. Solving, a=7 and b=3, so the product is 21.