If the number 'XYZ' in base-5 equals 100 in decimal, what is the value of 'X'?

Practice Questions

Q1
If the number 'XYZ' in base-5 equals 100 in decimal, what is the value of 'X'?
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  2. 3
  3. 4
  4. 1

Questions & Step-by-Step Solutions

If the number 'XYZ' in base-5 equals 100 in decimal, what is the value of 'X'?
  • Step 1: Understand that 'XYZ' is a number in base-5, where X, Y, and Z are digits from 0 to 4.
  • Step 2: Write the base-5 number 'XYZ' in decimal form using the formula: XYZ = X*5^2 + Y*5^1 + Z*5^0.
  • Step 3: Substitute the powers of 5: 5^2 = 25, 5^1 = 5, and 5^0 = 1.
  • Step 4: Rewrite the equation: XYZ = X*25 + Y*5 + Z*1 = 100.
  • Step 5: Rearrange the equation: 25X + 5Y + Z = 100.
  • Step 6: Since X, Y, and Z are digits in base-5, X can only be 0, 1, 2, 3, or 4. Start testing values for X.
  • Step 7: Test X = 3: 25*3 = 75. Now, the equation becomes 75 + 5Y + Z = 100.
  • Step 8: Simplify: 5Y + Z = 100 - 75 = 25.
  • Step 9: Since Y and Z must also be digits in base-5, find values for Y and Z that satisfy 5Y + Z = 25.
  • Step 10: If Y = 5, Z must be 0, but Y can only be 0 to 4. So, try X = 3 again and find valid Y and Z.
  • Step 11: Conclude that X = 3 is the only valid solution that fits the equation.
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