Question

How many two-digit numbers leave the remainder 1 when divided by 5 ? Find the sum of all these
numbers ?​

Answer 1

Step-by-step explanation:

two digit no. are from 10 to 99

and no. divisible by 5 are (95-10)/5

= 17 numbers

and no. divided by 5 leave remainder 1 = (96-11)/5= 17 numbers

Answer 2

≡QUESTION≡

How many two-digit numbers leave the remainder 1 when divided by 5 ? Find the sum of all these  numbers ?​

                                                       

║⊕ANSWER⊕║

The two-digit numbers which leave the remainder 1 when divided by 5 are :

11, 16, 21, 26,.......86, 91, 96

In this A.P :

a = 11

d = 16-11 = 5

l = 96

n = ?

Tn = a+(n-1)d

96 = 11+(n-1)5

n-1 = 85/5

n = 17+1

n = 18

S₁₈ = 18/2 (22 + 17*5)

     = 9 * (22 + 85)

     = 9 * 107

     = 963