Now that we have the idea of predicates under our belt, we can finally express full "if-then" statements, such as "if the weather is nice, you should go outside." This can be expressed in snap using the block. Notice how the first slot is shaped just like a predicate block. if blocks only know how to handle yes/no questions, so you should only ever put predicate blocks into this slot. The C-shaped part of the if block is where you put the commands that should be run if the condition is true. Let's take a look at an example:

In the above example, we had several possible cases to consider. However, in many situations, there are only two main cases. Take for example, the following sentence: "If a number is divisible by 2, it is even. Otherwise it is odd." For these situations we have the block. It works like this:

Here, we didn't need to have an additional "if," because all whole numbers are either even or odd. If the boolean expression (x mod 2 = 0) evaluates to false, we know that the number is not even and thus must be odd.

If you haven't seen the block before, it reports the remainder (or "modulus") when the first input is divided by the second. For example, 5 mod 2 reports 1 because 5 / 2 = 2 remainder 1. This block is especially useful for checking whether a number is divisible by another, because the remainder will be 0. is the same as asking if x is divisible by 2 (i.e. that x is even).