The right formula: Why math is the key to a more equitable society

John Mighton is a mathematician, author and founder of Jump Math. His latest book is All Things Being Equal: Why Math is the Key to a Better World.

In a keynote address at the Calgary City Teachers’ Convention, I once asked 700 teachers why, when you divide seven by two-thirds, you are allowed to flip and multiply (or why seven divided by two-thirds is the same as seven times three halves).

7 ÷ 2/3 = 7 x 3/2

Someone in the audience yelled out, “Because you get the right answer.”

Over the past few years I’ve asked hundreds of people why, when dividing by a fraction, you can invert the fraction and multiply. Only a few have been able to give me a simple explanation. The vast majority will admit they learned this procedure as a rule that they never understood.