Question

Why do you think students makes mistakes with phrases such as "10 less than a number ​

Answer 1

10 < x

Explanation:

ten (10) less than (<) a number (x)

Answer 2

This is a often mistake when being asked to write an expression. The words "is less than" and "less than" have different meaning. The phrase, "is less than" means 6 < k. The phrase "less than" means 6 - k.

I'll make a example with your problem. (I am adding a "x" on it cause it's easier for me to interrupt. But means the same as yours.)

"10 less than a number x"

10 - x

"10 is less than a number x"

10 < x