Free Math Riddles: Number Tricks
Free Riddle:
Ms. Arroyo asked the class to see if they could find the sum of the first 50 odd numbers. As everyone settled down to their addition, Terry ran to her and said, "The sum is 2,500."
Ms. Arroyo thought, "Lucky guess," and gave him the task of finding the sum of the first 75 odd numbers. Within 20 seconds, Terry was back with the correct answer of 5,625.
How does Terry find the sum so quickly?
Riddle Answer?
Hint:
Consecutive odd numbers are 1, 3, 5, 7....
Start with the first several odd numbers and look for a pattern.
Think for a while and when you guess the answer, scroll down to find the answer at the bottom of this page. More Hard Funny Riddles and Puzzles:
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Riddle Answer:
The following pattern holds: The sum is equal to n x n, when n is the number of consecutive odd numbers, starting with 1.
For example, the sum of the first 3 odd numbers is equal to 3 x 3, or 9; the sum of the first 4 odd numbers is equal to 4 x 4, or 16; the sum of the first 5 odd numbers is equal to 5 x 5, or 25; and so on.
