What do two minus make

Dividing positive and negative numbers. Practice: Dividing negative numbers. Why a negative times a negative is a positive. Why a negative times a negative makes sense. Multiplying negative numbers review. Dividing negative numbers review. Next lesson. Current timeTotal duration Google Classroom Facebook Twitter. Video transcript Lets say you are an Ancient Philosopher who was building up mathematics who was building mathematics from the ground up And you already have a reasonable of what a negative number could or should represent and you know how to add and subtract negative numbers But now you are faced with a conundrum What happens when you multiply negative numbers?

Either when you multiply a positive number times a negative number Or when you multiply two negative numbers So, for example You aren't quite sure what should happen if you were to multiply and im just picking two numbers where one is positive and one is negative What would happen if you were to multiply 5 times negative 3 You're not quite sure about this just yet You're also not quite sure what would happen if you multiply two negative numbers.

So lets say negative two times negative 6 This is also unclear to you What you do know, because you are a mathematician, is however you define this or whatever this should be It should hopefully be consistant with all of the other properties of mathematics that you already know And preferably all of the other properties of multiplication That would make you feel comfortable that you are getting this right.

Subscribe to our FREE newsletter and start improving your life in just 5 minutes a day. Numbers that are less than zero are known as 'negative' numbers. Probably the easiest way to visualise negative and positive numbers is using a number line, a tool with which you may well be familiar, especially if you have children at primary school.

A number line can help you to visualise both positive and negative numbers and the operations adding and subtracting that you can do with them. When you have an addition or subtraction to calculate, you start at the first number and move the second number of places either to the right for an addition or left for a subtraction.

This number line is a simplified version, but you can draw them with every number included if you wish. The big advantage of a number line is that it is very easy to draw for yourself on the back of an envelope or a piece of scrap paper, and it is also quite hard to go wrong with the calculation. As long as you are careful to count the number of places that you are moving, you will reach the correct answer. This time you start at and move 23 places to the right.

You can see straight away that the answer is 6. If you subtract a negative number, the two negatives combine to make a positive. Instead, you can think of it as turning one of the negative signs upright, to cross over the other, and make a plus. For clarity, you would never write two negative signs side by side without brackets. So if you are asked to subtract a negative number, it will always have brackets around it so that you can see that the use of two negative signs was intentional.

Once you have the numerical answer, then you can apply a very simple rule to determine the sign of the answer:. As a side issue, this goes some way to explaining why you cannot have the square root of a negative number there is more about this in our page on Special Numbers and Concepts. The square root is the number that is multiplied by itself to get the number.

You cannot multiply a number by itself to get a negative number. To get a negative number, you need one negative and one positive number. The rule works the same way when you have more than two numbers to multiply or divide. An even number of negative numbers will give a positive answer. An odd number of negative numbers will give a negative answer. But here you have one negative and one positive number, so the sign of the answer will be negative.

Again, you have one positive and one negative number, so the sign of the answer will be negative. This time, you have two negative numbers, so the sign of the answer will be positive.