How do you solve 5 x 3?  Not with 5 + 5 + 5, apparently.

The parent of a third-grader shared a picture of their child's perplexingly-corrected Common Core-style math quiz.

The student correctly answered "15" but was penalized for writing "5 + 5 + 5" instead of "3 + 3 + 3 + 3 + 3."

The student was docked another point for mixing things up again on an array representation of 4 x 6, even though they got the final answer right.

It all seems completely foreign to many parents who grew up memorizing multiplication tables and other basic arithmetic.

Many argue that in cases like this, a student's common sense correct answer is frustratingly seen as wrong. 

But experts swear by the system, arguing it helps teach children the underlying concepts of mathematics.

Frustrated Dad Writes Hilarious Common Core Check to Child's School

Texas 7th-Grader: Teacher Told Me to Admit God Is Not Real

Twice-Deported Illegal Immigrant Charged with Rape, Kidnapping

'It Stinks': 10-Year-Old Says Common Core Is 'Nonsense'