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The fifth triangular number is 15

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Q: What is the fifth triangular number?
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Continue Learning about Basic Math

Is the number 707 a triangular number?

707 is not a triangular number. The closest triangular numbers to 707 are 703 and 741.


Is 55 a triangular number?

Yes, 55 is a triangular number.


How do you check if a number is a triangular number?

you need to use this formula: n(n+1) T=--------- 2 So number times (number + 1) divided by 2. If the number you get is the same number as n its a triangular number. if it isn't well it isn't a triangular number.


Is 707 a triangular number?

no


How do your use triangular numbers to make square numbers?

The sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxxThe sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxxThe sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxxThe sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxx