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You are here Our Science & Maths Work Weekly Maths Challenges

Each week we ask our pupils to try our online Maths Challenge through the school's Virtual Learning Environment. This is accessible only by password. Here is a selection of recent problems.



Which square is the odd one out? Use the letters and numbers to identify the square when writing your answer.

Answer: B1

Which square is the odd one out? Use the letters and numbers to identify the square when writing your answer.


Correct answer: B3
(This square has two triangles in it, the others only have one).

Dan the detective looked for a number.
He found a two-digit number less than 50.
The sum of its digits was 12.
Their difference was 4.
What number did Dan find?

Answer: 48

When John is twice as old as he is now, he will be 3 times as old as he was 3 years ago. What age is he now?


Answer: 9 years old . Congratulations to John Varghese who correctly worked this tricky problem out. Explanation: This is a secondary school problem but it can be worked out by trial and error.
Trial and Error Method:

John's age must be bigger than 3 but let us start by trying his age at 6 and working up from there.

2 X 6 = (6 - 3) X 3  or 12 = 9 *NO
2 X 7  = ( 7 - 3) X 3  = 14 = 12 *NO
2 X 8  = ( 8 - 3) X 3  = 16 = 15 *NO
2 X 9  = ( 9 - 3) X 3  = 18 = 18 * CORRECT

James has between 30 and 50 ears of corn to feed his free range chickens. He counts them in fours and he has three left over. When he counts them in fives, he has one left over. How many does he have? Answer: 31
Explanation: See explanation below.
Eoin and his seven friends collect some money from selling eggs at the HWH-Bunclody football match. The average amount of money they have collected is 15 Euros. Another boy then puts in his money and the average is now 16 Euros. How much did the last boy add to the collection? Answer: 24.
Explanation : Eoin and his 7 friends makes 8 people in total. The average is 15. So to get the total we multiply the average (15) by the number of people (8) - 8 X 15 = 120. When another boy joins it makes 9 people. The average now is 16. To get the total we again multiply the average (16) by the number of people (9)- 9 X 16 = 144. The total for 8 is 120 and the total for 9 is 144. The difference is 24 and this is what the last boy contributed. 
John and James are working together collecting cocoa beans. It takes them 4 hours. John does twice as much work as James. How long would it take John to do the job alone? Answer: 6 hours

The newly established MC & BLACK Mini Company  (the company also sells kindling, eggs and turf by the way) decide to shine shoes on St. Patrick's Day. The company charges €2 to clean and polish each pair of shoes. The boys buy a bright box to store all the tins of shoe polish. In the box all but six tins are black, all but six tins are brown and all but six tins are neutral. How many tins of polish are in the box?

Answer: 9

Much of the information given in the problem was simply put there to confuse you. The cost of polishing the shoes had nothing to do with the actual question! The difficulty in the question was in how it was phrased "all but six are black" - if this was said as the following " six tins are not black" - it would have been much easier.

John has as many brothers as sisters, but his sister Natalia has only half as many sisters as brothers.
How many children are in the family? Answer: 7 (John, brother, brother, brother, Natalia, sister, sister)
Pat the Baker, was making his way to visit his mother in his delivery van. He had some loaves of bread that he had just baked that evening. He stopped at 3 villages on his way home. At each village in turn he gave half of the loaves he had left plus 2 extra to some of the children in the street. By the time he reached his mother's house he had one loaf left for them to share. How many loaves had he baked? (Answer: 24)

A boat anchored in Wexford harbour has a ladder which hangs over the side. The length of the ladder is 200cm, the distance between each rung in 20cm and the bottom rung touches the water. If the tide rises at a rate of 10cm an hour in Wexford when will the water reach the fifth rung?

Answer: It will never reach the fifth rung as the tide will raise both the boat and the ladder together!

What number is missing from this magic square.

Answer in photo to the right. Click on either photo to visit the famous church in Barcelona.


Row 1: 1
Row 2: 1
Row 3: 2
Row 4: 3
Row 5: 5
Row 6: 8
Row 7: 13 (The next number is found by adding up the two numbers before it.)

This sequence of numbers is known as the Fibonacci Sequence

Answer: The three numbers missing are 4, 6, 4

Each number is got by adding the two numbers immediately above it. This triangle is known as Pascal's Triangle.

A group of Miss Kelly's senior infants stand holding hands in a large circle in the assembly hall and Miss Kelly walks around the circle giving each child in order a number 1, 2, 3, 4, ... If number 12 is standing opposite number 30, how many children are there in the circle?

Answer: Let c be the number of children in the circle. Half the children, c/2, will be in-between child 12 and child 30.

So 12 + c/2 = 30.

Therefore c/2 = 18.

That is, there are 36 children

To promote the launch of a new chocolate bar SuperValuon Carrigduff is offering a, "buy four, get one free" deal. If each chocolate bar costs thirty cents, how much would ten chocolate bars cost?

Answer: If we get five for the price of four, ten will cost the same as eight. Hence ten chocolate bars will cost 8 times 30 cents = €2.40.