() * () Category Operators Type Reporter

The () * () block is an Operators block and a Reporter block. The block multiplies the two values and reports the result.

The numbers can be typed directly into the block, or Reporter blocks can be used instead.

This block can be stacked inside itself - this can be used to fit more numbers in or calculate exponents.

## Example Uses

In many projects, numbers must be multiplied; this block will do the job.

Some common uses for the () * () block:

• Scripts in calculator simulations
```set [result v] to ((a) * (b))
```
• Multiplying lists of numbers
```set [result v] to (1)
set [item v] to (1)
repeat (length of [numbers v])
set [result v] to ((result) *  (item (item) of [numbers v]))
change [item v] by (1)
end
```
• Math formulas
```([sqrt v] of ((((y1) - (y2)) * ((y1) - (y2))) + (((x1) - (x2)) * ((x1) - (x2))))) //Pythagorean Theorem
```
• Score multipliers
```set [score v] to ((score) * (2))
```
```when gf clicked
set [velocity v] to [0]
forever
if <key [space v] pressed?> then
change [velocity v] by (2)
set [velocity v] to ((velocity) * (0.87)) //simulates friction slowdown
```
• 3D Projects

## Scientific Notation

In Scratch 1.4 and previous versions, it sometimes converts very large numbers into scientific notation to save space. Scientific notation is simply the number in the form a*10b. These can be converted to a normal number by performing any mathematical function on it, such as adding. So if a variable named "number" has a value of 3*103 and you want to display it as a normal number, you can change it by:

`((number) + (0))`

It will then report "3000".

## Workaround

Main article: List of Block Workarounds

With natural numbers, this block can be replicated with the following code, assuming a is the first number and b is the second number:

```set [product v] to [0]
repeat (b)
change [product v] by (a)
```

The following code works for all cases (with the conditional). It divides by the reciprocal, the equivalent of multiplying.

```if <(b) = (0)> then
set [product v] to [0]
else
set [product v] to ((a) / ((1) / (b)))
end
```

The following code accepts negative numbers with decimals:

```delete (all v) of [num1 numbers v] //setup
delete (all v) of [num2 numbers v]
delete (all v) of [product digits v]
set [product v] to [0]
set [dec pos 1 v] to [0]
set [dec pos 2 v] to [0]
set [count v] to [1]
set [no 1 negative v] to [y]
else
set [count v] to [0]
set [no 1 negative v] to [n]
end
change [count v] by (1)
if <not <(letter (count) of (answer)) = [.]>> then
else
set [dec pos 1 v] to ((length of (answer)) - (count))
end
end
set [count v] to [1]
set [no 2 negative v] to [y]
else
set [count v] to [0]
set [no 2 negative v] to [n]
end
change [count v] by (1)
if <not <(letter (count) of (answer)) = [.]>> then
else
set [dec pos 2 v] to ((length of (answer)) - (count))
end
end
set [num1 v] to (num1 numbers)
set [num2 v] to (num2 numbers)
repeat (num1) //start
change [product v] by (num2)
end
set [decimal position v] to ((dec pos 1) + (dec pos 2))
set [count v] to [0]
repeat (length of (product))
change [count v] by (1)
add (letter (count) of (product)) to [product digits v]
end
if <not <(decimal position) = [0]>> then
insert [.] at ((length of [product digits v]) - ((decimal position) - (1))) of [product digits v]
end
if <<<(no 1 negative) = [y]> or <(no 2 negative) = [y]>> and <not <<(no 1 negative) = [y]> and <(no 2 negative) = [y]>>>> then
insert [-] at (1 v) of [product digits v]
end
set [product v] to (product digits)
```