Explanation:
The decimal numeral system (also called base ten or occasionally denary) has ten as its base. It is the numerical base
most widely used by modern civilizations.^{ }
A decimal is a
tenth part, and decimals become a series of nested tenths
http://en.wikipedia.org/wiki/Decimal
The kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI, from the French Le Système International d'Unitès), which is the modern standard
governing the metric system. The kilogram is defined as being equal to the mass
of the International Prototype Kilogram (IPK), which is almost exactly equal
to the mass of one liter of water.
SI
multiples
SI multiples for gram (g)

Submultiples


Multiples

Value

Symbol

Name

Value

Symbol

Name

10^{−1} g

dg

decigram

10^{1} g

dag

decagram

10^{−2} g

cg

centigram

10^{2} g

hg

hectogram

10^{−3} g

mg

milligram

10^{3} g

kg

kilogram(Our solved example in
mathguru.com uses this concept)

10^{−6} g

µg

microgram (mcg)

10^{6} g

Mg

megagram (tonne)

10^{−9} g

ng

nanogram

10^{9} g

Gg

gigagram

10^{−12} g

pg

picogram

10^{12} g

Tg

teragram

10^{−15} g

fg

femtogram

10^{15} g

Pg

petagram

10^{−18} g

ag

attogram

10^{18} g

Eg

exagram

10^{−21} g

zg

zeptogram

10^{21} g

Zg

zettagram

10^{−24} g

yg

yoctogram

10^{24} g

Yg

yottagram

Common prefixes are in bold face.

http://en.wikipedia.org/wiki/Kilogram
3 + 2 = 5 with apples
Addition is a mathematical operation that represents combining collections
of objects together into a larger collection. It is signified by the plus sign (+). For example, in the picture on
the right, there are 3 + 2 applesmeaning three apples and two other appleswhich
is the same as five apples. Therefore, 3 + 2 = 5. (Our solved example in mathguru.com uses
this concept)
Besides counting fruits, addition can also represent combining
other physical and abstract quantities using different kinds of numbers: numbers,
fractions, irrational
numbers, vectors, decimals and more.
http://en.wikipedia.org/wiki/Addition
Subtraction
"5 − 2 = 3" (verbally, "five minus two
equals three")
An example problem
Subtraction is one of the four
basic binary arithmetic operations; it is the inverse of addition, meaning that if we start
with any number and add any number and then subtract the same number we added,
we return to the number we started with. Subtraction is denoted by a minus sign in infix
notation.
Subtraction is used to model four related processes:
1. From
a given collection, take away (subtract) a given number of objects. For
example, 5 apples minus 2 apples leaves 3 apples.
2. From
a given measurement, take away a quantity measured in the same units. If I
weigh 200 pounds, and lose 10 pounds, then I weigh 200 − 10 =
190 pounds.
3. Compare
two like quantities to find the difference between them. For example, the
difference between $800 and $600 is $800 − $600 = $200. Also
known as comparative
subtraction.
4. To
find the distance between two locations at a fixed distance from starting
point. For example if, on a given highway, you see a mileage marker that says
150 miles and later see a mileage marker that says 160 miles, you have traveled
160 − 150 = 10 miles. (Our solved example in
mathguru.com uses this concept)
http://en.wikipedia.org/wiki/Subtraction
The above explanation is copied from
Wikipedia, the free encyclopedia and is remixed as allowed under the Creative
Commons Attribution ShareAlike 3.0 Unported License.