The mathematical rational for the 7/47 figure is what you are working out is the VAT on the gross amount ie the 17.5% of the total figure including the 17.5% VAT so the figure you are working out is 17.5%/117.5%. if you divide by 2.5% gives you 7/47 (that's the basis of it).
Same logic for 20% VAT ie what you are working out is 20% VAT on the total figure including the VAT ie 20%/120% or 1/6 if you divide by 6.
Now who knows the fraction when the 15% rate what present??? That's your maths question for tonight.
Should have been a maths teacher rather than an accountant, lol.
A really good explanation which I understand, so I say VAT fraction for 15% is 3/23. I must say I am really interested in the ins and outs of VAT. Am I being the sad one now lol.
I always multiply by xx/1xx to find the VAT amount and by 100/1xx to find the figure before VAT, replacing the xx with the VAT rate. No need to remember several different fractions that way
3/23 is correct (15/115 lowest common denominator 5)
I'm with Bill, for me its all about percentages not so much fractions (I can never remember them anyway and would need to work them out - so don't see the point)