Solve this math problem in your head divide 30 in half then add 20
Answer: The question said IN half, not BY half.
According to Prof Paul Brians from Washington State University:
‘If you are talking about dividing numbers or objects into two equal parts, the expression to use is “in half,” not “divide by half.” Technically, to divide a number by 1/2 is the same as to multiply it by 2.’
So 80 is definitely the answer when dividing BY half, but the answer is 35 when dividing IN half.