Find the sum of all 2 digit no divisible by 2 or 5
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Step-by-step explanation:
The two digit natural numbers divisible by 5 are
10,20......90,95
The series forms an A.P
an = a + (n-1)d
95 = 10 + (n-1) 5
95-10 = (n-1)5
85/5 = n-1
17 = n-1
17+1 = 18 = n
Sum of n numbers in a series is given by,
Sn = n/2(a+an)
= 18/2 (10+95)
= 9×105
= 945
Sum of all two digit numbers divisible by 5 is 945.
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