Math CentralQuandaries & Queries


Question from Bob, a parent:

4+4x5+4= ?

Hi Bob,

I really dislike this question. No mathematician or user of mathematics would write such an expression. Mathematical expressions are written to clearly state a fact or relationship so that someone else reading the expression will understand it. I expect this question comes from a textbook and is meant to confuse you rather than make it clear what is expected. The convention you are expected to use is that multiplication is performed before addition. Thus when you see $4 + 4 \times 5 + 4$ you are expected to perform the multiplication, $4 \times 5,$ first and get

\[4 + 4 \times 5 + 4 = 4 + 20 + 4 = 28\]


About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS