Not every number in a word problem is needed for the calculation. Sometimes one is missing, too.
Here's how:
1. Read the question. What do you have to find out?
2. Look for the numbers you need. Write a number that has nothing to do with the question under "Don't need".
3. If a number you need is missing, you cannot calculate. Then check "Something is missing".
Example: A club buys 12 jerseys at 35 dollars each and pays with 500 dollars. It has 85 members. The members are not needed: 12 × 35 = 420 and 500 − 420 = 80.
Example
A train travels for 4 hours at 120 km per hour. It has 9 cars. Then it goes another 75 km. How many kilometers does the train travel in all? 555 (you don't need 9)
A theater has 18 rows with the same number of seats. Today 640 tickets are sold. How many seats are still free? Missing: how many seats one row has
For parents
What does this exercise practice?
Read carefully even with several steps, spot numbers that are not needed and notice when a problem cannot be solved because something is missing.
Common pitfalls
Many children calculate with every number in the text, even the number of members or cars. Ask what each number belongs to.
How to practice at home
While shopping, ask a math question and add a number that is not needed. Does your child find it?