What is the unit digit of the sum of first 111 whole numbers?
5
The first 111 whole numbers are \(0, 1, 2, \dots, 110\). Since adding 0 does not change the sum, this equals the sum of the first 110 natural numbers.
\[S=\frac{n(n+1)}{2}=\frac{110\times 111}{2}=55\times 111=6105\]
The unit digit of \(55\times 111\) is the unit digit of \(5\times 1=5\). Therefore the unit digit is 5.
Similar Questions
Let x = (433) 24 – (377) 38 + (166) 54 . What is the units digit of x?
Important Questions from Unit Digit
The unit digit in 4 × 38 × 764 × 1256 is:
How many times does the number 3 occur in unit's place for numbers ranging from 1 to 100?
A. 20
B. 11
C. 10
D. 19
Find the unit digit in the given factor (3451) 51 × (531) 43 .
A. 6
B. 4
C. 1
D. 9
What is the unit digit of 178 × 593 + 157?
Find the unit digit of $(123)^{123} \times (347)^{347} \times (568)^{568}$.
