aliensbrain
  • Home
  • Study
  • Quizzes
  • 🎤AI Practicefree
  • Notebooks
  • Community
  • Sign in
  • Math & Logic Puzzles
  • A number added to twice itself gives twenty-one. Find tha...
Multiple choice general knowledge math & puzzles

A number added to twice itself gives twenty-one. Find that number!

  1. 8

  2. 7

  3. 3

  4. 9

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let the number be x. The problem states x + 2x = 21. Combining like terms: 3x = 21. Dividing both sides by 3: x = 7. Checking: 7 + 2(7) = 7 + 14 = 21.

Keep practicing — related questions

  • There is a number that is 3 times the sum of its digits. What is this number?
  • A natural number gets doubled when added to its reciprocal. Find that number!
  • There is a number that is 3 times the sum of its digits. What is this number?
  • A natural number is doubled when added to its reciprocal. Find thatnumber!
  • How many of the following numbers are divisible by 132 ?264, 396, 462, 792, 968, 2178, 5184, 6336
  • How many of the following numbers are divisible by 132 ?264, 396, 462, 792, 968, 2178, 5184, 6336
  • An accurate clock shows 8 o'clock in the morning. Through how may degrees will the hour hand rotate when th...
  • It was Sunday on Jan 1, 2006. What was the day of the week Jan 1, 2010?
Play the full quiz 🎤 Practise this topic out loud

Practice this topic

  • Number Operations and Properties (896 questions)
Advertisement
© Aliensbrain | all rights reserved
  • About
  • Contact
  • Terms and Condition
  • Privacy Policy