There was a plastic bag of things sling over the lady's right forearm while she was fiddling with her mobile phone with the other hand.
She opened the calculator function on her mobile phone and started pressing some numbers.
"78+42/2," she typed.
Then she erased and retyped, "78+42=120/2=60."
78+42 may be a little difficult for some of us. But 120/2?
He wondered if she was really bad in math, too tired to think, just lazy or it's just too convenient to just flip out the phone.