Monday, December 13, 2010

Decimals and rational numbers

Place Values
Reading and writing decimals
1208.0925
one thousand two hundred eight and nine hundred twenty-five ten-thousandths
Models for decimals
decimal square intereactive games (must download to play)
Equality of Decimals
.4 = .40 = .400
Inequality of Decimals
.47 < .6
Even though 47 is greater than 6 more of the square is shaded for .6 than .47
Place value test for inequality of decimals
The greater of two positive decimals that are both less than on will be the decimal with the greater digit in the tenths place.  If the digits are equal you move to the digit to the right and so on.
Rational numbers
Any number that can be written in the form a/b where b does not = 0 and a and be are integers.
Dark blue shaded area
Terminating decimal
If a rational number is a/b is in simplest form it can be written as a terminating decimal if and only if b has obly 2s and or 5s in its prime factorization.
repeating decimals:
Rounding
Decimals can be rounded to the nearest whole number, tenth, hundreth, ect.
  •  Find which place value the number is to be rounded to and check the digit to the right
  • If the digit on the right is 5 or greater then all digits to the right are dropped and you round up
  • If the difit on the right is less then 5 then all the digits to the right are dropped and the place value number stays the same

No comments:

Post a Comment