Simplify the expression 0.2y3+0.3y3+0.1y3 use integers or decimals for any numbers in the expression.

All are rational numbers. Any integer is such, and the others as written can be expressed as finite fractions ie

168 / 100
5111 / 1000
9111 /1000

If your notation means that the repeating decimal goes on forever eg

5.111111111111111111111111111111111111111..................

Then it still can be rational, as 46 / 9 is, and 82 / 9

Quick-Start Guide When you enter an expression into the calculator, the calculator will simplify the expression by expanding multiplication and combining like terms. At this point the calculator will attempt to factor the expression by dividing a G C F, and identifying a difference between two squares, or factorable trinomials. Use the following rules to enter expressions into the calculator. Variables Any lowercase letter may be used as a variable. Exponents Exponents are supported on variables using the ^ (caret) symbol. For example, to express x 2, enter x ^ 2. Note: exponents must be positive integers, no negatives, decimals, or variables. Exponents may not currently be placed on numbers, brackets, or parentheses. Parentheses and Brackets Parentheses ( ) and brackets [ ] may be used to group terms as in a standard expression. Multiplication, Addition, and Subtraction For addition and subtraction, use the standard + and - symbols respectively. For multiplication, use the * symbol. A * symbol is optional when multiplying a number by a variable. For instance: 2 * x can also be entered as 2x. Similarly, 2 * ( x + 5 ) can also be entered as 2 ( x + 5 ) ; 2 x * ( 5 ) can be entered as 2 x ( 5 ). The * is also optional when multiplying parentheses, example: ( x + 1 ) ( x - 1 ). Order of Operations The calculator follows the standard order of operations taught by most algebra books - Parentheses, Exponents, Multiplication and Division, Addition and Subtraction. The only exception is that division is not currently supported; attempts to use the / symbol will result in an error. Division, Square Root, Radi cals, Fractions Division, square root, radi cals, and fractions are not supported at this time. A future release will add this functionality.

that's all I can say basically I learned it this way.

All integers are rational numbers. The easiest way to see that is to write an integer as a fraction with 1 as a denominator; 4=4/1=8/2; 5=5/1.
Any number that can be written as a ratio of two integers numbers is by definition a rational number ( it is a ratio---rational).
Any decimal number with a periodic decimal part can be cast as a fraction, so it is rational.
An irrational number is a number that cannot be written as a fraction.
Examples: PI, sqRT(2), Sqrt(3), SQRT(5), e. There is an infinite number of them.

You do the operation to get a decimal number.
Isolate the integer part (to the left of the decimal point)
Convert the non integer part (decimal part) into a fraction.
Write the result as (integer part) (fraction part)
3/2=1.5
Integer part is 1, decimal part is 0.5
0.5 as a fraction is 1/2
3/2= 1 1/2

Isolate the integer part (to the left of the decimal point)
Convert the non integer part (decimal part) into a fraction.
Write the result as (integer part) (fraction part)
3/2=1.5
Integer part is 1, decimal part is 0.5
0.5 as a fraction is 1/2
3/2= 1 1/2

1. Put a decimal mark at the end of one integer in the expression, 15./2 or 15/2. or 15./2. all give 7.5 as result
   
2. OR press [diamond][ENTER] to force conversion of a fraction to a decimal number,
3. OR press [MODE][F2] and scroll to line EXACT/APPROX, press right arrow to unfold the menu list and select [3:Approximate]
   

Hello,
Since this is a discrete distribution, you can only calculate it at integer values of the variable. Hence the last argument in the function (0.75) must be an integer. As you gave a decimal number where an integer is required, the calculator returns a domain error.
Hope it helps.

Hello,
Press [MATH][1:ToFrac] to convert an aswer to fraction.
If you enter 18.52[ToFrac] [ENTER gives 463/25

[MATH][2:ToDEC] converts a fraction to a decimal number.
Hope it helps.

Hello,
Your TI81 can only perform numerical calculation: It always give uour numbers. The TI89, a more sophisticated calculator, can of course do numerical calculation, BUT ALSO symbolic ones. You ask it for the derivative of sin(x) and it will give you cos(x).
Anyway, if you want a decimal result for you calculation above one of the numbers must have a decimal point (instead of writing 2PI write 2.PI.

The TI 89 can do exact calculations. But if you want approximate results any number in the sequence of operations must have the mark of a decimal. Numbers without decimal marks are considered integers, Integer numbers with a decimal mark are treated as floating point numbers ( meaning decimal).

Hope it clarifies things for you.

If i type 10+10 it comes up with 10+10=20 and my setting is on Math G . So mabey try that ?