Find the sum of the unit digits of first 99 whole numbers
Answers
Answered by
4
Answer:
450
Step-by-step explanation:
The numbers to look at are
1, 2, 3, ..., 10,
11, 12, 13, ..., 20,
...
91, 92, 93, ...., 99.
The sum we want is then
1 + 2 + 3 + ... + 9 + 0 [ numbers 1 to 10, group 1 ]
+ 1 + 2 + 3 + ... + 9 + 0 [ numbers 11 to 20, group 2 ]
+ 1 + 2 + 3 + ... + 9 + 0 [ numbers 21 to 30, group 3 ]
+...
+ 1 + 2 + 3 + ... + 9 [ numbers 91 to 99, group 10 ]
= ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 ) × 10
= 45 × 10
= 450
Answered by
3
Answer:
nmtc ka question number 32 chapter 1
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