The worksheet "Follow the Clues to Find the Correct Phone Login Code" features fun brainteaser activities that help students practice place value in multi-digit numbers.

Each page begins with clues. Each clue includes math terminology or problems that help students discover which digits to type into a phone in order to unlock it.

Second-grade pages feature place value terms, like instructing students to put the number 6 in the thousands place and the number 4 in the tens place. Third-grade pages ask students to solve problems, like finding the missing number in a pattern and putting it in the hundreds place, or writing the sum of two numbers and putting it in the tens place. Third-grade pages also include a section at the bottom where students can double-check their work. It lists the sum of the numbers in the code so students can add the numbers they wrote in the blanks and see if it's the same.

Place value is an important math concept for students to understand. It provides a basis for numerical understanding. It makes arithmetic possible when students know what digits represent in each number. It also helps with estimation, and it provides the basis for more advanced math, like working with decimals.

Students can identify the place value of each digit in a number. You can also give them a written number, like 'four hundred and thirteen,' and ask them to write it as a number.

Puzzles and brainteasers can be a fun way for students to practice when more conventional exercises feel boring. For example, students could write the correct four-digit code to unlock a phone according to clues that are listed about each digit. This activity can also be a good way for students to review other math concepts, like asking them to find the sum of 4 and 3 and write the digit in the thousands place.

Students can complete place value riddles, like using a certain set of numbers to create the largest number possible, or they can create a number where all of the digits add up to a given number. Students in upper grades can read sets of riddles in order to find the right answer.