() * () (block)

"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))

• Velocity

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*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 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

• () + ()
• () - ()
• () / ()