# Checking answer for a time 11:45

Another checking answer question-- how to see if a student entered a correct time. 11:45 to be specific.

Never mind! I think I got it-- correct: this.latex=“11:45”

Do you need format too (i.e. 1145 vs 11:45)? You still might want to use countNumberUsage to avoid incorrects because of spaces or whatever.

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You could probably do a more complete job checking here, but maybe this is a start? 11:45? â¢ Activity Builder by Desmos

Avoids countNumberUsage as well

Tricky. I think that’s awesome!

That’s neat, but I don’t get how it is working, yet! Have to stare at it some more. So fun!

Getting there on the understanding of the approach! Here is the AB if interested. I’m trying to use the “Three Reads with Problem Stem” strategy here. Thinking about useful feedback as well-- text based. Doing some sort of super cool Desmos interaction would be great?? Needed?? ROI?

He essentially made the time part of a conditional function. Without the variable name “11:45” would look like this:

`f(x)={x=11:45,0}`
which essentially says “if x=11, then f(x)=45. Otherwise, f(x)=0.”

Then, he evaluates the student expression at 11, which should be 45 if correct. Any other evaluation is 0. If a student entered 10:45, 11 would evaluate at 0, because the student function would be:
`f(x)={x=10:45,0}`

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