Page 8 - SM inner class 6.cdr

Large Numbers used in Daily Life Rules for Rounding
Situations Here's the general rule for rounding:

We know that we use meter (m) as unit of v If the number you are rounding is
length, kilogram (kg) as a unit of weight and followed by 5, 6, 7, 8, or 9, round the
litre (l) as a unit of volume and second (s) as a number up.Example: 38 rounded to the
unit of time. nearest ten is 40.

For example, in the case of length or distance, v If the number you are rounding is
we use centimetre for measuring the length of followed by 0, 1, 2, 3, or 4, round the
a pencil, as it is small, metre for measuring
number down. Example: 33 rounded to
length of a saree and kilometre (km) for
the nearest ten is 30
measuring distance between two places. But
for measuring the thickness of a paper, even
What Are You Rounding to?
centimetre is too big. So we use millimetre
(mm) in this case. When rounding a number, you first need to
Since there is a relationship between all of ask: what are you rounding it to? Numbers can
them. We need to know about this conversion be rounded to the nearest ten, the nearest
and convenient usage. hundred, the nearest thousand, and so on.
10 millimetres = 1 centimetre Consider the number 4,827.
100 centimetres = 1 metre
v 4,827 rounded to the nearest ten is 4,830
1000 metres = 1 kilometre
( Q 7 is at ones place)
the number of millimetres in 1 kilometre is
calculated as: v 4,827 rounded to the nearest hundred is

1 km = 1000 m 4,800 ( Q 2 is at ten place)
= 1000 × 100 cm v 4,827 rounded to the nearest thousand is
= 1000 × 100 × 10 mm 5,000 ( Q 8 is at hundred place)
= 10,00,000 mm
All the numbers to the right of the place you
In the same way we buy rice or wheat in are rounding to become zeros. Here are some
kilograms. But items like spices, chillipowder,
more examples:
haldi etc. which we do not need in large
quantities, are bought in grams (g). v 34 rounded to the nearest ten is 30
1000 g. = 1 kg v 6,809 rounded to the nearest hundred is
A bucket normally holds 20 litres of water. But 6,800
some times we need a smaller unit, the v 1,951 rounded to the nearest thousand is
milliliters. A bottle of hairoil, painting colour 2,000
etc. lable in milli litres (ml) and oil tankers,
water in reserviours are marked with Rounding to the Nearest Ten Thousand
kiloliteres (kl) To round the numbers to the nearest ten
1000 litres = 1 kilolitre thousand, make the numbers whose last four

digits are 0001 through 4999 into the previous
Rounding Off Numbers
lower number that ends in 0000.
We round off a number by taken to its nearest
convenient whole number. As 48 is nearer to For example:– 54,424 rounded to the nearest
50 than 40, so 48 may be rounded up to 50. ten thousand would be 50,000.
This is called rounding off the number. In the Numbers that have the last four digits of 5000
process of rounding of a number, it is taken to or more should be rounded up to the next even
its closest whole number.
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Mathematics In Focus - 6