Number System Quiz
1️⃣ What is the sum of the first 5 positive even numbers?
Step-by-Step Explanation
The first 5 positive even numbers are 2, 4, 6, 8, and 10.
Adding them: 2 + 4 + 6 + 8 + 10 = 30.
Answer: 30 ✅
2️⃣ Which of the following numbers is a prime number?
Step-by-Step Explanation
A prime number has only two factors: 1 and itself.
17 is the only number here that meets this condition.
Answer: 17 ✅
3️⃣ What is the value of 15% of 80?
Step-by-Step Explanation
15% of 80 can be written as (15/100) × 80 = 12.
Answer: 12 ✅
4️⃣ If a number is doubled and then 5 is added, the result is 21. What is the number?
Step-by-Step Explanation
Let the number be 'x'. 2x + 5 = 21.
Solving for x, we get x = 8.
Answer: 8 ✅
5️⃣ What is the smallest 4-digit number that can be formed using 0, 1, 2, and 3 without repetition?
Step-by-Step Explanation
The smallest possible 4-digit number is 1023 (since 0 cannot be the leading digit).
Answer: 1023 ✅
6️⃣ The sum of two numbers is 45, and their difference is 15. What are the two numbers?
Step-by-Step Explanation
Let the two numbers be x and y.
Given: x + y = 45 and x - y = 15.
Adding the two equations: 2x = 60, so x = 30.
Substituting x = 30 in x + y = 45: 30 + y = 45, so y = 15.
Answer: 15 and 30 ✅
7️⃣ If the product of two numbers is 216 and their HCF is 6, what is their LCM?
Step-by-Step Explanation
We know that the product of two numbers = HCF * LCM.
Given: Product = 216, HCF = 6.
So, 216 = 6 * LCM.
LCM = 216 / 6 = 36.
Answer: 36 ✅
8️⃣ A number when divided by 119 leaves a remainder of 19. What is the remainder when it is divided by 17?
Step-by-Step Explanation
Let the number be 'N'.
N = 119k + 19, where k is an integer.
119 is divisible by 17 (119 = 17 * 7).
So, N = (17 * 7k) + 19.
19 divided by 17 leaves a remainder of 2.
Therefore, N when divided by 17 will leave a remainder of 2.
Answer: 2 ✅
9️⃣ Find the number of trailing zeros in 50! (50 factorial).
Step-by-Step Explanation
Trailing zeros are formed by pairs of 2 and 5 in the prime factorization.
Since there are more 2s than 5s, we count the number of 5s.
50/5 = 10.
50/25 = 2.
Total = 10 + 2 = 12.
Answer 12 ✅