The **Teen numbers 2** exercise appears under the Early math Math Mission. This exercise continues strengthening the user's understanding of how groups of tens and ones are used to name numbers and give them value.

## Types of problems

There are three types of problems that show up in this exercise:

- Remaining number past: This problem uses objects and asks users to identify how many are left when ten are removed from a certain number. The user also has to use a multiple choice toggle to describe the meaning of the tens and the ones in the context of the problem.
- Fill in meaning: This problems asks the user to identify in context the meaning of the tens and ones digit of a two-digit number.
- Order and fill in beyond ten: This problem has two parts. The first is to put numbers in increasing order. The second is to answer how far each number that was ordered is beyond ten.

## Strategies

- Accuracy badges are easy for those that know two-digit numbers well. The speed badges are a hard to achieve because of the many different types of problems and different answer types that are needed.

## Real-life Applications

- Knowing how to count is essential for learning algebra and the higher maths, and counting is used for almost everything humans do.