Mathematical riddles often form a part of aptitude tests and entrance exams. Most of them are arithmetic, algebra or number logic puzzles. Puzzles are basically devised to test your brain power and memory. In this series of articles, we have compiled various types of simple math riddles. Each article contains a set of 10 maths puzzles with answers and explanations. Solve the given questions and evaluate your mental abilities:
Q.1.I bought a car with a peculiar 5 digit numbered license plate which on reversing upside down could still be read. On reversing value is increased by 58212. What is the original number if all digits were different?
Only 0 1 6 8 and 9 can be read upside down. Therefore the original number must be 10689 and the number after reversing upside down is 68901, only then the difference given can be generated.
Q.2.Aman has a certain number of apples with him. He gives half of the apples and then half an apple to Mohit. Then he gives half of the remaining apples and then half an apple to Rahul. And in the same way he gives to Rohit. After giving it to Rohit, he has 9 apples. What is the number of apples that Aman was having in the beginning.?
Solve this question backwards and get the answer as 79 apples. You can apply the formula as (apples in the end 2 + 1) and apply this formula as many times as is the number of persons to whom he has distributed the items given.
Q.3.If 20 boys and 20 girls eat 20 apples in 20 minutes, in how many minutes will one boy and one girl take to eat one apple ?
Since 20 boys and 20 girls eat 20 apples in 20 minutes, means they will eat 1apple in 20 minutes. It will be 20 minutes and not one minute.
Q.4.Sita and Gita were walking on the road.
Sita said, "I weigh 55 Kgs. What is your weight?"
Gita replied that she wouldn't disclose her weight directly as she is obese. But she said, "I weigh 50 Kgs plus one third of my weight." Find the weight of Gita?
Solving mathematically, let's assume that her weight is X Kgs.
X = 50 + X/3
3*X = 150 + X
X = 75 Kgs
Q.5.Following facts are true about Ludhiana:
No two citizens have exactly the same number of coins.
No citizen has exactly 2025 coins.
There are more citizens than there are coins with any one citizen.
What is the largest possible number of the citizens of Ludhiana?
It is given that no citizens have exactly 2025 coins. Hence there are 2025 citizens with 0 to 2024 coins.
Suppose there are more than 2025 citizens. But these will violate the condition that "There are more citizens than there are coins with any one citizen." As for any number more than 2025, there will be same number of citizens as the maximum number of coins with any citizen.
Q.6.There are 70 employees working with Bulls Eye of which 30 are females. Also, 30 employees are married. 24 employees are above 25 years of age. 19 married employees are above 25 years, of which 7 are males. 12 males are above 25 years of age. 15 males are married. How many unmarried females are there and how many of them are above 25?
15 unmarried females & none are above 25 years of age.
Simply put all given information into the table structure and you will get the answer.
Q.7.You have six 8's and you may use any of the (+, -, /, ×, .) as many times as you like. How many arithmetical expressions which use the six 8's to form 1000 are possible?
There are 3 such expressions.
(888/.888) = 1000
(8/.8) × (8/.8) × (8/.8) = 1000
(888-88)/.8 = 1000
Q.8.What is the four-digit number in which the first digit is 1/4 of the second, the third is the sum of the first and second, and the last is two times the second?
It is given that the first digit is 1/4 of the second. There are 2 such possibilities.
1 and 4
2 and 8
Now, the third digit is the sum of the first and second digits.
1 + 4 = 5
2 + 8 = 10
It is clear that option 2 is not possible. So we are left with only one options. Also, the last digit is two times the second. Hence, the answer is 1458.
Q.9.Two people enter a race in which one runs to a point and back. Anil runs 20 mph to and from the point. Sunil runs to the point going 10 mph and 30 mph going back. Who came in first?
Let's assume that the distance between start and the point is D miles.
Total time taken by Anil to finish = (D/20) + (D/20) = D/10 = 0.1D
Total time taken by Sunil to finish = (D/10) + (D/30) = 2D/15 = 0.1333D
Thus, Anil is the Winner.
Alternatively, note that initially speed of Anil (20 mph) was twice the speed of Sunil (10 mph). Hence, when Anil (20 mph forward) reached the point, Sunil (10 mph forward) was halfway. When Anil (20 mph back) finished, Sunil (still 10 mph forward) reached the point.
Thus, Anil wins the race and by that time Sunil covers only half the distance, no matter how far the point is!!!
Q.10.In the General meeting of "Bulls Eye Society", Poonam said, "The repairs to the Society will come to a total of Rs 3120 and I recommend that this amount should be met by the members, each paying an equal amount." The recommendation was immediately agreed. However, four members of the Society chose to resign, leaving the remaining members to pay an extra Rs 26 each.
How many members did the Society originally have?
Assume that there were initially N members.
As 4 members resigned and remaining members paid Rs 26 each, it means that total amount of 4 members is equal to Rs 26 each from remaining (N-4) members.
Thus, 4 * (3120 / N) = 26 * (N - 4)
12480 = 26N2 - 104N
26N2 - 104N - 12480 = 0
Solving the quadratic equation we get N=24.
Hence, the Society originally had 24 members.