The set of integers is formed by the positive and negative integers and zero. They are important for everyday life, especially in situations involving negative values, such as temperature scales, bank balances, altitude indications in relation to sea level, among others situations. Additions and subtractions involving these numbers require the use of mathematical rules involving the positive (+) and negative (–) signs. We must also emphasize the study of the module of a number, which means working the absolute value of a digit, note:
Let's determine the modulus of the following numbers:
Module + 4 = |+4| = 4
Module –6 = |–6| = 6
Module –10 = |–10| = 10
Module +20 = |+20|=20
Addition and subtraction of whole numbers without parentheses.
1st property → equal signs: adds and conserves the sign.
2nd property → different signs: subtracts and keeps the sign of the number with the greatest modulus.
+ 5 + 6 = + 11 → 1st property
+ 9 + 10 = +19 → 1st property
– 6 + 2 = – 4 → 2nd property
+ 9 – 7 = +2 → 2nd property
– 3 – 5 = –8 →1st property
–18 – 12 = –30 → 1st property
Addition and subtraction of whole numbers with the presence of parentheses.
To eliminate the parentheses we must perform a sign game, note:
+ ( + ) = +
+ ( – ) = –
– ( + ) = –
– ( – ) = +
After removing the parentheses, just apply the 1st or 2nd property.
+ (+9) + (–6) → + 9 – 6 → + 3
– (– 8) – (+6) → +8 – 6 → +2
+ (– 14) – (– 8) → –14 + 8 → – 6
– (+ 22) − (– 7) → –22 + 7 → –15
– ( + 9 ) + (– 12) → – 9 – 12 → – 21
by Mark Noah
Graduated in Mathematics
Brazil School Team
Numerical sets - Math - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/matematica/operacoes-entre-numeros-inteiros.htm