O game of signs is composed of rules that make it easy to operate two or more whole numbers more quickly and efficiently, these rules come from the definitions of addition, subtraction, multiplication and division of whole numbers.
The rules of the sign game depend on the operation that is being wrapped between whole numbers, if we have an addition or subtraction, we will use one rule, if we have a multiplication or division, we will use another.
Plus and minus sign game rule
The following rule is used only for addition and subtraction of whole numbers.
different signs
Keep the sign of the larger number and subtract the numbers normally.
→ Example 1
– 7 + 8 =
As the signs are different, we must keep the sign of the largest number, in the case (+), and then subtract the numbers (8 – 7 = 1). Therefore:
– 7 + 8 = +1
→ Example 2
+15 – 7 =
Similarly, we will keep the sign of the major number (+) and subtract the numbers (15 – 7 = 8), then:
+15 –7 = + 8
Read too: Studies of the signs of a 2nd degree function
equal signs
Keep the sign and add the numbers.
→ Example 1
– 9 – 8 =
As the signs are now equal, just keep the repeating sign and add the numbers normally, such as 9 + 8 = 17, then:
–9 – 8 =–17
→ Example 2
– 4 – 66 =
Likewise, repeating the sign and adding the numbers, we have:
–4 –66 = – 70
→ Example 3
+33 + 67 =
+33 + 67 = +100
Rule of sign games for multiplication and division
The rule is now exclusively for when we perform operations using the multiplication Or the division. For this purpose, the table known as the sign set is valid.
first number sign |
second number sign |
result sign |
+ |
+ |
+ |
+ |
– |
– |
– |
+ |
– |
– |
– |
+ |
To solve these operations, we must first operate the signs according to the table and then operate the numbers.
→ Example 1
(+ 4) · (–12) =
Operating the signs initially, we have that (+) with (–) is equal to (–); and since 4 multiplied by 12 is equal to 48, we have:
(+ 4) · (–12) = – 48
→ Example 2
(– 55): (– 11) =
Analogously, we have that (–) with (–) is equal to (+); and since 55 divided by 11 is equal to 5, we have:
(– 55): (–11) = +5
→ Example 3
(35) · (– 5) =
When no sign appears in the number, we can consider it as positive, so the result of this example will be a negative number, because (+) operated with (–) is always (–).
(35) · (– 5) = –175
→ Example 4
(– 81): (+ 9) =
Initially, we have that (–) with (+) is equal to (–); and as 81 divided by 9 is equal to 9, then:
(–81): (+ 9) = – 9
See too: Even or odd?
