Arithmetical & Geometrical Progression Calculator
Arithmetical Progression:
a :
l :
n :
d :
S :
l = a + (n - 1) * d,
S = (a + l) * n / 2
(Enter any three fields above)
a : first term considered
l : last term considered
n : number of terms
d : common difference
S : sum of n terms
Geometrical Progression:
a :
l :
n :
r :
S :
l = a * r(n - 1)
,
S = (r * l - a) / (r - 1)
(Enter any three fields above)
Note: Two combination (l,n,S) and (a,n,S) don't work because of formula conflict!
a : first term considered
l : last term considered
n : number of terms
r : ratio of progression
S : sum of n terms
Example: The highest speed of a motor is 450 rpm. The lowest speed is 100 rpm. There are 10 speed. What is the ratio between successive speeds?
Answer: r = (n-1)√l/a = (10-1)√450/100 = 9√4.5 = 1.182