Mathematical Riddle: Find the Sum of First 75 Odd Numbers
Read this classroom riddle and try to find the answer.
In a classroom, a Math’s teacher is asking questions to her students.
She first asked the class to see if they could find the sum of the first 50 odd numbers. As everyone settled down to their addition, Mark ran to her and said, \’The sum is 2,500.\’
The teacher was surprised so to test if Mark actually calculated the sum or was guessing she gave him the task of finding the sum of the first 75 odd numbers.
Within 20 seconds, Mark was back with the correct answer
How does Mark find the sum so quickly and what is the answer??
So were you able to solve the riddle? Leave your answers in the comment section below.
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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.
So the first 75 odd numbers would be 75 x 75 which is equal to 5625