*"Times" redirects here. For other uses, see Time (disambiguation).*

() * () | |

(() * ()) | |

Category |
Operators |

Type |
Reporter |

Introduced in |
11Oct03 |

The **() * ()** block is an Operators Block and a Reporter Block. The block multiplies the two values given 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 that require calculations

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
- Calculating factorials

when gf clicked ask (Number) and wait set [counter v] to (answer) repeat ((answer) - (1)) change [counter v] by [-1] set [output v] to ((output) * (counter))

## 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*10^{b}. 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*10^{3} 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 whole number and b is the second whole number:

set [product v] to [0] repeat (b) // where b should be a whole number (not negative and does not have a decimal) change [product v] by (a) end

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

set [product v] to ((a) / ((1) / (b)))

The following code accepts negative numbers with decimals:

delete all of [num1 numbers v] delete all of [num2 numbers v] delete all of [product digits v] set [dec pos 1 v] to [0] set [count v] to [0] repeat (length of (a)) change [count v] by (1) if <not<(letter (count) of (a)) = [-]>> then if <(letter (count) of (a)) = [.]> then set [dec pos 1 v] to ((length of (a)) - (count)) else add (letter (count) of (a)) to [num1 numbers v] end end end set [dec pos 2 v] to (0) set [count v] to (0) repeat (length of (b)) change [count v] by (1) if <not <(letter (count) of (b)) = [-]>> then if <(letter (count) of (b)) = [.]> then set [dec pos 2 v] to ((length of (b)) - (count)) else add (letter (count) of (b)) to [num2 numbers v] end end end set [num1 v] to (num1 numbers) set [num2 v] to (num2 numbers) set [product v] to [0] repeat (num1) 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 repeat until <[0] < ((length of [product digits v]) - ((decimal position) - (1)))> insert (0) at (1) of [product digits v] end insert [.] at ((length of [product digits v]) - ((decimal position) - (1))) of [product digits v] if <not <<(a) < [0]> = <(b) < [0]>>> then insert [-] at (1) of [product digits v] end set [product v] to ((product digits) + (0))

## See Also

() + ()
• () - () • () * () • () / () • Pick Random () to () • () < () • () = () • () > () • () and () • () or () • Not () • Join ()() • Letter () of () • Length of () • () Mod () • Round () • () of ()More blocks... |