The use of 'upon' to denote a fraction is now archaic in modern English, having been dropped before the mid-20th century in favour of other prepositions such as 'over' and 'out of', or forms such as 'x-y-ths', etc. However, it is still preserved as the standard term in Singapore English, as well as in other Asian Englishes such as South Asian English.
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definitions
preposition
used to denote a fraction, such as in 'three upon ten' (3⁄10).
- Wah, die liao. I got 4 upon 50 for my Maths test... - Wah piang, 4 upon 50? That's like 20% nia... didn't know your maths so jialat bro.