If you've ever been baffled by some of the modern methods used to teach our kids how to do simple sums, take heart from this exasperated parent's response.
As he struggled with his maths homework, the boy wrote a large question mark next to the task, which asked him to solve a simple subtraction question using a 'number line' – whatever that is.
And his parent was equally bewildered by the tortuous new method – so they decided to take matters into their own hands using a parent's favourite tool: sarcasm.
The solution, which has been posted to Facebook, went as follows:
"Don't feel bad. I have a Bachelor of Science Degree in Electronics Engineering which included extensive study in differential equations and other higher math applications.
"Even I cannot explain the Common Core mathematics approach, nor get the answer correct. In the real world, simplification is valued over complication.
"The answer is solved in under 5 seconds - 111.
"The process used is ridiculous and would result in termination if used."
She signs off: "Sincerely, Frustrated Parent"
Pure poetry for all of us left scratching our heads by maths 'strategies' taught at schools!
More on Parentdish: The trouble with maths