Question

A store has $11$ headphones, and a few more are added. Now, there are $18$ headphones in the store. Choose the correct addition equation for the total number of headphones.

• A. $18+0=18$
• B. $11+6=18$
• C. $11+7=18$
• D. $9-9=18$

Answer 1

The correct option is C $11+7=18$

Solution: Option C

Say: We need to identify the equation that correctly shows the total number of headphones in the store.

Ask:
How many headphones does the store have?
Ans: 11

How many are added?
Ans: We need to find this number.

How many headphones are there in the store now?
Ans: $18$

Then can we say that $11+$ __$=18?$
Ans: Yes

How will we find the number of headphones that were added?
Ans: By counting forward after $11$ till $18$.

So, how many headphones are added?
Ans: $7$

What equation will be framed?
Ans: $11+7=18$

Hence, Option C is correct.

WB: If required, use the whiteboard to represent the number of CDs as shown and write the addition equation.
Show how 10 units are grouped together to form 1 rod.

Probing Q: Since there were $11$ pairs of headphones before and now there are $18$, do we need to add $11$ and $18$, i.e. $11+18$, to find the number of headphones that were added?

Ans: No, we need to count forward after $11$ till $18$ to find the number of headphones that were added.