Record arithmetic expressions in the program

Arithmetic expressions are written according to the following rules:

• You can not omit the multiplication sign between the factors and put two signs of operations side by side.
• The indices of array elements are written in square (school AY, Pascal) or round (Basic) brackets.
• Variables are used Latin letters.
• Operations are performed in order of precedence : first, the computation of functions, then the exponentiation, then the multiplication and division, and last of all, addition and subtraction.
• Operations of one seniority are performed from left to right . However, in school AA there is one exception to this rule: erection operations are performed from right to left. Thus, the expression 2 ** (3 ** 2) in the school AJ is calculated as 2 ** (3 ** 2) = 512. In the QBasic language, the similar expression 2 ^ 3 ^ 2 is calculated as (2 ^ 3) ^ 2 = 64 And in the Pascal language the operation of raising to a power is not provided at all, in Pascal x ^ y is written as exp (y * ln (x)), and x ^ y ^ z as exp (exp (z * ln (y)) * ln (x)).

Examples of writing arithmetic expressions

Math notation	Record in school algorithmic language
	x * y / z
	x / (y * z) or x / y / z
	(a ** 3 + b ** 3) / (b * c)
	(a [i + 1] + b [i-1]) / (2 * x * y)
	(-b + sqrt (b * b - 4 * a * c)) / (2 * a)
(x <0)	sign (x) * abs (x) ** (1/5)
	0.49 * exp (a * a - b * b) + ln (cos (a * a)) ** 3
	x / (1 + x * x / (3 + (2 * x) ** 3))

Typical errors in writing expressions: