Page 16 - Arithmetic

15. 12492 + 12493 41 = 4
42 = 16
43 = 64
44 = 256 and so on...
The unit digits when the power of 4 is even = 6
The unit digit when the power of 4 is odd = 4
In the question, one power is odd and other is even The sum of the unit’s digits = 6 + 4 = 10
Therefore, the unit place will have 0.
16. Natural numbers are 1,2,3,4...30 The series is in A.P
Sn = 𝑛 [first term + last term] 2
n = 30
First term = 1 Last term = 30
Sn =30[1+30]=15×31=465 2
17. Three digits number divisible by 8 are 104, 112, 120...992
This is an AP series
Tn = a + ( n – 1) d
992 = 104 + (n -1) × 8 888 = 8(n-1)
111 = n – 1
n = 112
Page 15 of 55
Arithmetic Concept