There is no such thing as a "triangular" number (as a number), a triangular number or triangle number counts the objects that can form an equilateral triangle. One object can and Three objects can but not Two objects.
The formula for the nth triangular number is n(n+1)/2. Therefore, the fourth triangular number is equal to 4 x (4+1) / 2 = (4 x 5) / 2 = 10. The fiftieth triangular number is equal to 50 x (50+1) / 2 = (50 x 51) / 2 = 1275.
The 20th triangular number is 20*21/2 = 210
yes it is!EDIT: No, it is not.
The 81st triangular number is 3321 The nth triangular number is given by tn = n(n+1) ÷ 2 The 81st triangular number is: t81 = 81(81+1) ÷ 2 = 3321
No. ---- The nth triangular number (n must be a whole number > 0) is given by: tn = 1/2 n(n+1) Testing for 49: 1/2 n(n+1) = 49 → n2 + n - 98 = 0 → n = (-1 ± √393)/2 but 393 is not a square number, so n cannot be a whole number which it must be for a triangular number; thus 49 is not a triangular number.
The formula for the nth triangular number is n(n+1)/2. Therefore, the fourth triangular number is equal to 4 x (4+1) / 2 = (4 x 5) / 2 = 10. The fiftieth triangular number is equal to 50 x (50+1) / 2 = (50 x 51) / 2 = 1275.
The nth triangular number is n(n+1)/2
The nth triangular number is n(n+1)/2
The 20th triangular number is 20*21/2 = 210
The formula for the nth triangular number is n(n+1)/2. If the 8th triangular number is 36, then we can set up the equation 8(8+1)/2 = 36. Solving for n, we get n = 7. Therefore, the 7th triangular number is 7(7+1)/2 = 28.
yes it is!EDIT: No, it is not.
The 81st triangular number is 3321 The nth triangular number is given by tn = n(n+1) ÷ 2 The 81st triangular number is: t81 = 81(81+1) ÷ 2 = 3321
The Nth triangular number is calculated by: N(N + 1) -------- 2 Hope this is useful!
36 is a triangular number. The formula for the nth triangular number is, n(n + 1)/2. So, 36 is the 8th triangular number : 8 x 9/2 = 36
The nth triangular number is n(n+1)/2, so the 2000th triangular number is 2000 * 2001 / 2 = 2,001,000
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.
The nth triangular number is n(n+1)/2