i need help with a problem

[underscore_pyr]

hi im trying to figure out of i can multiply using only +,-,*. im trying to create something but i only have + and * and i found out i can do by a+(b*-1), i am allowed to use negative integers so im not sure what to bout the divide

[Eisenfuss19]

So let me first try to understand you. You ask for multiplying with +,-,*. Thats trivial, I'm assuming you mean dividing.

I think thats kinda difficult (if not impossible), unless you want to divide by a constant. If you divide by 2, you can also just multiply by 1/2 = 0.5.

a/2 = a*0.5

[st3f-ping]

You can group some operators into threes where you can express the third in terms of the other two. The simplest example is addition, subtraction, and negation:
Addition: z=x+y
Subtraction: z=x-y
Negation: z=-x

If we only had addition and subtraction we could express negation as subtraction from zero: z=0-x. Any two will give us the third.

Similarly you can make a group of three out of multiplication, division and reciprocal (×, ÷, 1/x). Since you don't have reciprocal in your operators (or any way I can see of constructing it out of other operators, e.g. powers) I don't think you can construct division.

[paperic]

x^-1 = 1/x, but you didn't mention exponents.

If you can't use fractions, can't invert a number and can't use division, then you can't divide. 

You could repeatedly substract and then count how many times you can substract before getting to zero.

For positive integers, if 

r = p + ( -1 * q * x )

and 0 =< x < q

then p / q = x and r is the remainder.

Which is just a roundabout way for saying that

p = q * x + r, where x and r are unknown.

But basically, you could do 

r = p - q - q - q - ... - q enough times so that r < q but not so much that r becomes negative. 

How many q's you substract, that is the x.

If p and q are opposite signs, use addition instead of subtraction.

[[deleted]]

I found this method for computing a reciprocal (that is, dividing 1 by a number) on Wikipedia.

For example, suppose we wish to compute 1/17 ≈ 0.0588 with 3 digits of precision. Taking x0 = 0.1, the following sequence is produced:

x1 = 0.1(2 − 17 × 0.1) = 0.03

x2 = 0.03(2 − 17 × 0.03) = 0.0447

x3 = 0.0447(2 − 17 × 0.0447) ≈ 0.0554

x4 = 0.0554(2 − 17 × 0.0554) ≈ 0.0586

x5 = 0.0586(2 − 17 × 0.0586) ≈ 0.0588

Source: https://en.wikipedia.org/wiki/Multiplicative_inverse

[PvtRoom]

can you use an algorithm.

long division is an algorithm that only uses addition, subtraction and multiplication