please understand my doubt

Question

The digit in the units place of a number is equal to the digit in the
ten place of half of that number and the digit in the ten place of that
number is less than the digit in units place of half of the number by 1.
If the sum of the digits of the number is 7 then what is the number

 

i have fully solved solution in my book what i want

i want to know how you conclude "of" meaning in this question
for ex. look first statement "the digit in the ten place of half of that number"
in this statement of came two times
i not understanding meaning first "of" is it for about half to number? or it means to multiply

how you conclude "of" meaning what point you observe in sentence then you conclude this meaning is right in context of the sentence or problem. according to me of have two meaning first is multiplication second is about or concern something so how can i find out which is appropriate?

this "meaning of" question is not for only this problem this is for
every word problem please try to explain the meaning of "of"

give some example so i easy understand

Answer 1

In a mathematical context, OF means MULTIPLY; but in normal English used to state a problem, of has the meaning 'belonging to' as is usually encountered in speech.

 

one third of thirty means "one third multiplied by thirty" i.e. 10.

 

one third of my salary goes to rent of my house shows two different "ofs", the first being multiplication, the second introducing a modifier clause