Description:
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I use a fomular as the first paramter and the result is wrong. 
When brackets were set, the result is correct, but this makes no sense to me.

Reproduce code:
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echo round(0.35*90/100);
echo number_format(0.35*90/100, 2, ".", "");

to get the correct result I should use the following syntax:
echo round(0.35* (90/100) )
echo number_format(0.35* (90/100) , 2, ".", "");

Expected result:
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0.32
0.32

Actual result:
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0.31
0.31