Writing Expressions

Words turn into signs. Plus, more than, increased by and sum mean add. Minus, decreased by and difference mean subtract. Times, twice and product mean multiply, and divided by and quotient mean divide.

So "a number n increased by 9" is n + 9, "the product of 6 and a number n" is 6n, and "a number n divided by 2" is n / 2. Find the word for the operation, then write the numbers and the letter around it.

"4 more than a number n" means start at n and add 4: n + 4. Writing 4 + n is just as right, because adding in any order gives the same total. On the board you type the expression as a new line, and the board checks that it says what the words say.