# add, subtract, 2 numbers respecting the priorities of the operators

Online math exercise > Middle School > 7th Grade > operations on integers and decimals

What is the result of `(10+9)+(2-4)-(3+10)`.

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### Prime numbers

A **prime number** is an integer greater than or equal to 2 that has no divisors other than 1 and itself.

#### Decomposition in product of primes

Any integer greater than or equal to 2 is prime or product of primes.

When we write an integer as a product of prime numbers, we say that we
decompose this integer into a product of prime numbers.

### Percentage

A
percentage
is defined as a proportionality coefficient expressed as a fraction with a denominator of 100.

To calculate p% of a number is to multiply that number by `p/100`.

### Euclidean division

Performing Euclidean division of a by b,
is equivalent to determining two numbers, the **quotient (q) and the remainder (r) such that a = b*q + r** .

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