Question

The sum of all two-digit numbers is :
(a) 4750
(b) 4895
(c) 4905
(d) None of these​

Answer 1

Answer:

c.4905

Step-by-step explanation:

Arithmetic progression :

Sn = n/2 [2a + (n-1)d]

n = 90,

a = 10,

d = 1

Sn = 90/2*[2*10 + (90-1)1]

= 45 * (20+89)

= 45 * 109

= 4905

Sn = 4905

Answer 2

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The sum of all two-digit numbers is :

(a) 4750

(b) 4895

(c) 4905✔️

(d) None of these

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