Idea 4of 23Builds on3n means 3 times n
Words into an expression
How do you turn words into an expression?
Today you'll discover
- why giving away means take away
- why “7 less than n” is n − 7
- how “double” becomes 2n
Think firstRaj gave 7 of his stickers away
Which expression shows how many stickers Raj has left?
Decide first, then press Next. Say what happens first, then what happens next.
A bag marked n with 7 dashed squares beside it, taken out. Then the expression n − 7, the words 7 less than a number, and with 15 in the bag, 15 − 7 = 8. The last step shows the words 4 more than double a number.
See the whole ideathe big idea and the key word, in one place
The big idea
Write what happens, in order: “7 less than a number” is n − 7.
Words to symbols
Each phrase has its own symbols.
- 5 more than nn + 5
- 5 less than nn − 5
- double n2n
- half of nn ÷ 2
Easy to get wrongSubtraction order matters: n − 7 takes 7 from n, and 7 − n takes n from 7. They are not the same.
Key word
- less than
- in words like “7 less than a number”: start with the number and take 7 away, n − 7
Ready to use it?
- Write an expression from words.
- Say an expression in words.