Sign in. It’s quick, free and it’s up to you.
An account is an optional way to support the work we do. Find out more.
MATHS WEEK STARTS today, and as is our annual tradition here, we’re setting you some puzzles with all the answers published on the site tomorrow at 1pm.
Get puzzling!
Question 1
Which is the smallest value?
a) 67%
b) 2/3
c) 8/13
d) 0.666
Question 2
What is one half of two-fifths of 20 times 3?
a) 12
b) 25
c) 5
d) 14
Question 3
A recent TheJournal.ie report on energy drinks told us that over 26 million litres of energy drinks are consumed in Ireland per year. One product popular with young people is sold in 500ml cans. Each of these contains 55g of sugar. Suppose someone was to drink 1 can of this a day for a year, how much sugar would they consume in a year from this source alone?
a) 2.17 kg
b) 3.65 kg
c) 20.075 kg
d) 5.5 kg
Question 4
Last Thursday was the 10th day of the 10th month. 10 multiplied by 10 is 100, which of course is a square number. How many more times will this happen (ie. the product of the day and the month being a square number) before the end of this year?
a) 1
b) 2
c) 3
d) 4
Question 5
The following shape, equivalent to five squares, was cut out of cardboard to make a box. The perimeter is 72 cm. What is the area of cardboard in centimetres squared?
a) 72 cm sq
b) 120 cm sq
c) 180 cm sq
d) 144 cm sq
Question 6
Which is the best value?
a) Half a square metre for €10
b) Half a metre squared for €5
c) They are both the same
d) None of the above
Question 7
My age is 4 times what it was 4 years ago minus twice what it will be in 4 years’ time. What’s my age?
a) 16
b) 18
c) 24
d) 26
Question 8
Which is best value per litre from these special offers of the same product originally marked €4 per litre?
a) 1 litre for €3.49
b) 1 litre with 20% off marked price
c) 3 for the price of 2
d) 33% extra free
Question 9
The government increased the carbon tax in the budget by €6 per tonne of carbon dioxide (CO2) released. A petrol car can emit 2.31kg of carbon dioxide from burning 1 litre of fuel. How much extra would this cost for a petrol car with a fuel efficiency of 16 km/l driving 10,000 km in a year?
a) €56
b) More than €100
c) €28
d) less than €10
Question 10
The following maths puzzle went viral in Japan, as most people will fall into the same trap and get the incorrect answer. Can you solve it correctly?
9 – 3 ÷ ⅓ + 1 = ?
The answers will be published on the site at 1pm on Sunday. Let us know how you get on in the comments.
To embed this post, copy the code below on your site
I like sums but would ye not put a gap between the answers, kgb)… that’s the end of answer a attached to answer b… just saying
@Pat Corrigan: that irritated me too! esp when you can use letters in maths!
I could answer them all correctly if I wanted to but I don’t want to ruin it for others. I’ll read the answers tomorrow just to make sure ye have em all right.
d, a, c, b, c, b, c, c, d.
And then to Q 10.
Any proper mathematician will use brackets when framing a question. This question, and ones like it, are purposefully made to annoy people. However that said in this case use BODMAS and the answer is 1.
9 – 3 ÷ 1/3 + 1 = 9 – (3 ÷ 1/3) + 1 = 9 – (3*3) + 1 = 9 – 9 + 1 = 1
@Alan Rossiter: But yet…..
….the key bit is the 3 ÷ 1/3.
÷ and / both mean ‘divide by’ and thus carry equal weight in BODMAS.
Therefore 3÷1/3 is the same as 3÷1÷3. As they have equal value in terms of BODMAS then start from the left. The 3 on the left divided by 1 equals 3. That 3 divided by 3 equals 1. Therefore the equation now turns into 9-1+1 = 9.
And this sort of potential inexactness is exactly why no mathematician would ever frame that question that way in the first place!
I’m sorry I started. I was nearly asleep!
@Alan Rossiter: Q1 is c, rather than d.
And as for Q10, your first answer is right, as is the reason why these things always go around Facebook and the like with people fighting over the answer.
But 3 ÷ One Third (using words for clarity) isn’t the same as 3 ÷ 1 ÷ 3, as division isn’t associative (i.e., the order you do the operations matters). In fact, because division isn’t associative, 3 ÷ 1 ÷ 3 isn’t a well defined mathematical statement, as you get two different answers depending on the order of operations chosen.
@John Nolan: C it is. Damn.
@John Nolan: It’s true that 3 ÷ 1 ÷ 3 is not the same as 3 ÷ 1/3. However the question states the latter, which evaluates to 9. I don’t agree that there is any choice of orders of operation in this case. It’s equivalent to 3 ÷ 0.33333…
@Paraic: Yeah, I read it to myself as 3 divided by a third, which is 9 all day long. The way it’s written is not helpful. I don’t think I’ve used the divided by symbol (can’t even find it on my phone lol) since primary school.
@John Nolan: I was thinking that myself. Spot on with the other ones.
My brain tried but I am sure failed
You lost me at “have”
Q4 3rd of December is also a square number as well as 11/11 and 12/12
@Michael O’Carroll: I missed out on those, ran through it too quickly!
Is 1+1 still 2
C a c b c c is there a mistake in number 7? (Should D be 28?) C B …. and number 10 is ambiguous and a ridiculous assertion in there being one correct answer as you can use varied functions to achieve varied answers
@Declan Edward: 7 is fine. Set up your equation as follows : let x be the age now
x = 4(x-4) – 2(x+4)
x = 4x-16 – 2x -8
x = 2x – 24
24 = x
Check : 4 * 20 – 2 * 28 = 80-56=24.
Meh
Q.4 3rd December is also square as well as 11/11 and 12/12
@Michael O’Carroll: by their nature they have to be squared. It was a trick question.
BABBCBADA19
Jeez…it wouldn’t let me answer any of them…WTF!! Really!! Why do I waste my time?
c a c c c a c c d 1
have your say