Question

10 दिन लौट डिजिट इन द प्रोडक्ट ऑफ एनी 15 कंट्री टू टू डिजिट ओड नेचुरल नंबर​

Answer 1

Explanation:

All two-digit odd positive numbers are 11, 13, 15, 17, ...., 99. which are in AP with a=11,d=2,l=99

Let the number of terms be n.

a

n

=99

a+(n−1)d=99

11+(n−1)×2=99

n=45

Sum of n terms is given by

S

n

=

2

n

(a+l)

S

n

=

2

45

(11+99)=2475

Therefore, the sum of all two-digit odd positive numbers is 2475.