formula to find the sum of ap series
Arithmetic progression This sum can be found quickly by taking the number n of terms being added (here 5), multiplying by the sum of the first and last number in the progression (here 2 + 14 = 16), and dividing by 2:
Pi The Indian astronomer Aryabhata used a value of 3.1416 in his Āryabhaṭīya (499 AD).[58] Fibonacci in c. 1220 computed 3.1418 using a polygonal method, independent of Archimedes.[59] Italian author Dante apparently employed the value 3+√2/10 ≈ 3.14142.[59]