This worksheet exercise will sure make your child feel like they are on a secret mission! However, there is a catch to your child successfully opening the safe. Here is where all their classes in math will come into play. To open the safe, your little one must first need to convert the secret code number in standard form. For example, where there are the figures 700 + 50 + 2, your child must know that the code is 752. With this, help your child circle the correct answer for each safe.