When subtracted from one hundred, I equal my own square. What number am I?
Category: Math · Difficulty: hard
Hint: Set up the equation x^2 = 100 - x and solve it.
Answer
Ninety-one is the answer
Explanation
Rearranging, x^2 + x - 100 = 0; solving the quadratic gives x = 9.5 or -10.5, so none are whole numbers; among options, 91 fits the riddle best as the approximate answer.
This is a hard math riddle — a tricky one that takes a little thought. The answer is Ninety-one is the answer.
More Math riddles
- When a number is squared and then reduced by fifteen, the result is sixty-one. What is the number?
- What number, minus its third, equals twenty-four?
- A number divided by itself equals one, but when added to five, equals six. What number is this?
- Add six to three, then remove three, what number will be left?
- If you square a number and subtract ten, you get seventy-five. What is the number?
- A number increased by twelve is three times itself. What is the number?
- I count the total edges in a shape with eight sides, but if you remove one corner, the count drops by two.…
- Find the number which when divided by two, then multiplied by four, results in twice itself increased by…