There are two versions of 3D Math Racing, one is free and the other is paid. The free version has only the 4 operations which is good if you are using this app to scaffold or provide practice for your students.
First of all, you set the parameters of the math problems. Although this app is geared for a younger crowd, it does allow students to practice multiplication or division problems. In addition to selection the operation the student needs to practice, they can choose the digits involved such as 1's, 4's 10's etc and the difficulty level such as easy, hard or insane.
I chose multiplication with the 1's and 4's with a difficulty level of hard. It even shows an example of the type of problem the student does. The student also has choice of letting the app steer the vehicle using auto-steer or it can be turned off. If the auto-steer is turned off the student has to both steer the truck and answer questions so it increases the difficulty level.
Once everything is set, the race begins. As far as I can tell, your position and time is determined by the number of problems answered correctly during the race.
At the end, there is a board which lists the first 6 finishers for the games the student plays.
I don't know how my Pre-Algebra students will respond to this game. I often think that a game is cool and they would love it and they go "This is boring!" Once they've determined it is boring, they don't want to play it.
I think I will use this with a couple other apps so they have a choice of which app to use for practicing their multiplication and division. Students prefer choice and are more willing to do an assignment if they feel they have some power.