Q19. What is the sum of all digits which appear in all the integers from 10 to 100 ?
Detailed Solution
We need to calculate the sum of all digits from 10 to 100. 1. For numbers from 10 to 99: - Units digits: The digits 0, 1, 2, ..., 9 each appear 9 times (e.g., 10, 20, ..., 90 for 0; 11, 21, ..., 91 for 1).
The sum of digits from 0 to 9 is (9 * 10) / 2 = 45. So, the sum of all units digits is 9 × 45 = 405. - Tens digits: The digits 1, 2, ..., 9 each appear 10 times (e.g., 10-19 for 1; 20-29 for 2).
The sum of digits from 1 to 9 is 45. So, the sum of all tens digits is 10 × 45 = 450. - Total sum for numbers 10-99 = 405 (units) + 450 (tens) = 855. 2. For the number 100: - The digits are 1, 0, 0.
Their sum is 1 + 0 + 0 = 1. Adding these two parts: Total sum of all digits from 10 to 100 = 855 + 1 = 856.
More Quantitative Aptitude Questions
Q78. What is the 489th digit in the number 123456789101112...?...
DQ75. A set (X) of 20 pipes can fill 70% of a tank in 14 minutes. Another set (Y) of 10 pipes fills 3/8th ...
DQ76. If n is a natural number, then what is the number of distinct remainders of (1ⁿ + 2ⁿ) when divided b...
CQ77. Let P = QQQ be a 3-digit number. What is the HCF of P and 481?...
CQ5. 5. What is the least possible number of cuts required to cut a cube into 64 identical pieces?...
BMore from UPSC 2023 CSAT
Q1. Based on the above passage, the following assumptions have been made: 1. Collection, processing and ...
DQ2. Which one of the following statements best reflects the crux of the passage?...
CQ3. Based on the above passage, the following assumptions have been made: 1. Organic farming is inherent...
BQ4. Which one of the following statements best reflects the most logical, rational and practical message...
CQ5. Based on the above passage, the following assumptions have been made: 1. To implement the Sustainabl...
BAce UPSC with AI-powered Practice
LearnPro's test series adapts to your weak topics and shows real analytics.
Explore Courses →