Math brain teasers and puzzles often feature in competitive exams. Most of them are algebra, arithmetic or picture puzzles. Here is a compilation of puzzle-based questions grouped according to their level of difficulty. Each article contains a set of 10 maths puzzles with solutions. In this article, you will come across medium-level maths number puzzles devised to hone your mental aptitude.
Solve these questions and check your mental abilities:
Q.1. Fig. Shows a eight-by-eight square. How many squares are there in all?
Q.2. Nine kiwis look identical except the one which is lighter. How can you weigh only 2 times on a balance scale to find out which one is lighter?
If we give a number for each kiwi, say from 1 to 9. We put kiwi 1, 2, and 3 on the left and kiwi 4, 5 and 6 on the right and weight them. If they are balanced then we know kiwi 1 to 6 is OK. We just need to put kiwi 7 on one side and kiwi 8 on the other side and weight them. Now weighing them if one side is lighter, we get our lightest one. Otherwise, the one kiwi left aside will be lighter.
Q.3. Can you name the biggest number that can be written with two 1's and two 0's?
People often think of the number 1100 as the biggest number that can be written with two 1’s and two 0's.
But there is a number many, many times greater than this number, namely: 1010
In fact, 1010 is almost ten million times greater than 1100.
Q.4. What is the biggest number that can be written with four 9s?
Generally the biggest number that people often think with four 9s is the number 9999.
But the biggest number is a number many, many times greater than this number i.e., 9999
Thus, the biggest number 9999 is much greater than 9999.
Q.5. In the following question, one term in the number series is wrong, find out the wrong term.
1, 7, 56, 224, 448
The term of the series are (13-03), ( 23-13), (43-23), (63-33), (83-43). So 224 is wrong and must be replaced by (63-33)= 189.
Q.6. Find the wrong term in the series: 5, 27, 61, 122, 213, 340, 509
The terms of series are 23-3 , 33-3 , 43-3 , 53-3 , 63-3 .... and so on . So 27 is the wrong term which should be replaced by 33-3 = 24
Q.7. Complete the following series:
520, 738, ?, 1342
520 = 83+8, 738 = 93+9, 1342 = 113+11, so missing number is 103+10 = 1000 + 10 = 1010. So answer is 1010.
Q.8. I went on a holiday to a hill station. It snowed for 15 days. But when it snowed in the morning the afternoon was lovely. And when it snowed in the afternoon the day was preceded by a clear morning. Altogether there were 14 very nice mornings and 17 very nice afternoons. How many days did my holiday last?
Let the holiday lasted for x days. If 14 mornings were nice, then x - 14 evening had snow.
Similarly If 17 evenings were nice, then x - 17 morning had snow. So we have
x - 14 + x - 17 = 15 => x = 23.
Q.9. Shona wants a new garden with 12 trees. She decides to plant 6 rows of 4 trees each with rows can have common trees. Furthermore, she wants a symmetric garden. How will his garden look like?
The garden of Gautam would look as follows:
Q.10. What will come in place of "?"
The inner value is half of sum of squares of outer numbers.