Question
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  1. I think of a two-digit number.
    The ones digit is 6 more than the tens digit.
    The number is 12 more than the product of its digits.
    Find the original number.

Ask by Bryant Kelly. in Singapore
Mar 26,2025

Upstudy AI Solution

Tutor-Verified Answer

Answer

The original number is either 28 or 39.

Solution

Let’s denote the tens digit as and the ones digit as .
Given:
  1. The ones digit is 6 more than the tens digit:
  2. The number is 12 more than the product of its digits:
We can solve these equations to find the original number.
Solve the system of equations by following steps:
  • step0: Solve using the substitution method:
  • step1: Rewrite the expression:
  • step2: Substitute the value of
  • step3: Simplify:
  • step4: Move the expression to the left side:
  • step5: Calculate:
  • step6: Factor the expression:
  • step7: Separate into possible cases:
  • step8: Solve the equation:
  • step9: Calculate:
  • step10: Rearrange the terms:
  • step11: Calculate:
  • step12: Calculate:
  • step13: Check the solution:
  • step14: Rewrite:

    The solutions to the system of equations are or .
Therefore, the original number can be either 28 or 39.

Answered by UpStudy AI and reviewed by a Professional Tutor

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Extra Insights

Let’s have some fun solving this puzzle! We can start by defining the two-digit number as , where is the tens digit, and is the ones digit. From your clues, we know two things:
  1. The ones digit is more than the tens digit . So, .
  2. The number is more than the product of its digits: .
Substituting from the first equation into the second gives:
.
Now let’s simplify this equation!

.
Rearranging gives:
.
Factoring this quadratic equation results in:
.
So, or .
If , then (making the number 28).
If , then (making the number 39).
Checking both numbers against the second clue, we find that 39 fits because:
and .
So, the original number is 39!
Feel free to challenge yourself with more puzzles!

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