2026 · Q7
A number is formed by three digits, each less by unity than the digit that follows it. If 15 is added to the number, then the sum is 30 times the sum of the digits of the number. What is the product of the digits of the number?
Elementary MathematicsNumber System
- A6
- B24
- C60
- D120
Explanation
Let the digits be a, a + 1, a + 2 (each one less than the digit that follows it). The number is 100a + 10(a + 1) + (a + 2) = 111a + 12 and the digit sum is 3a + 3. The condition gives 111a + 12 + 15 = 30(3a + 3), i.e. 111a + 27 = 90a + 90. Solving, 21a = 63 so a = 3; the digits are 3, 4, 5 and their product is 60, option C.