Maths Question song

[Liam] 
You're insecure, so half of four, 
Your old brains are not what they were before, 

[Zayn] 
Add two threes, it's fine for us, 
'Cause we're young and we can still remember stuff 

[Harry] 
Everyone else can multiply by 60, 
Everyone else can add two 

[All] 
Now take off one hundred and add on 24, 
Then divide by two and add on seven more 
And if you're struggling now it's not hard to tell 
You don't know, (o oh) your maths skills are terrible 

[All] 
If only you had a mind like me 
You'd understand how to divide the sum by three, 
And then just add on the age of this OAP 
You don't know, (o oh) your maths skills are terrible (o oh) 

[Harry] 
It's really kinda pitiful