Pick any real number. Double it, add 14, divide the whole result by 2, and then subtract your starting number. What number will you always hold in your hand?
7
Algebraically: ((2x + 14) / 2) - x = (x + 7) - x = 7, regardless of the initial value of x.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Easy. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
More math riddles
If you write down all the whole numbers from 1 to 100 inclusive, how many times will you write the digit 7?
I am a prime number. If you reverse my digits, I become a composite number whose factors are 3 and 11. What number am I?
Ava gets 7 tulips on Monday and 4 tulips on Tuesday, then gives away 3. How many tulips are left?
Eli has 6 pumpkins and finds 7 more. How many pumpkins does Eli have now?
A buyer purchases ducks for $4 each and geese for $7 each, spending precisely $53. If the buyer obtained more ducks than geese and bought at least one of each, what was the total number of birds purchased?
Santa delivers 9 presents on each of 5 streets. How many presents is that?