Directions: Using the digits 1 to 9 at most one time each, place a digit in each box to make the smallest possible decimal sum. Source: Kari Frazier

Directions: Using the digits 0 to 9, at most one time, fill in the blanks to create sine and cosine functions with the given periods in degrees. Source: Kate Nerdypoo

Directions: Using the digits 0 to 9 at most one time each, place a digit in each box to make a derivative as close to 100 as possible. Source: Stephen Spinelli

Directions: Using the digits 0 to 9 at most one time each, place a digit in each box to make a true statement. Source: Julia Anker

Directions: Using the digits 0 to 9 at most one time each, place a digit in each box to make a time that is 3:57 pm. Source: Patty Stephens

Directions: Using the digits 0 to 9 at most one time each, place a digit in each box to create a true statement. Source: Stephen Caviness

Directions: Using the digits 0 to 9 at most one time each, place a digit in each box to find an odd modulus, an even modulus, and the smallest possible modulus. Source: Mark Ward

Directions: Using the digits 0 to 9 at most one time each to create a true statement. Source: Anthony Meli

Directions: Using the digits 1 to 9 at most one time each, to make one set of functions intersect exactly twice, one set of functions intersect exactly once, and one set of functions never intersect. Source: Mike Fouchet

Directions: Using the digits 0 to 9 at most one time each, create two similar triangles. You may have as many leading zeros as you like. Source: Drew Ross