How should you write the regular expression for height and what grade is the person in?

Question

Regular Expressions

Misha is in the 3rd grade, his height is 150 cm.

You need to write down a regular expression. My attempts were successful with '[0-9]+cm'.

Answer 1

One or more digits (remember)
Space
"class"
Many non-digits
One or more digits (remember)
Space
"cm"

Answer 2

\b\d{2,3} cm\b
\b\d{,2} class\b