# Rounding - SchoolRack

```NOTES:
Rounding Whole numbers to
N significant figures:
We round numbers if we only need
a reasonable approximation rather than
the exact value.
Whole number i.e.: numbers without
any decimal point (the decimal point is
implied).eg:120980
The first significant figure in a number
is the first non-zero digit (reading from
left to right).
All digits from 1-9 are significant.
Zeros in between non-zero digits are
also significant.eg: 2302006.all zeros in
this number are significant because
they occur between two non-zero
digits.
How to round a WHOLE number to
certain number of significant figures:
Steps:
1. Decide where you want to cut
off the number, and mark a &quot;cutoff point&quot;.
2. If the digit after the cut-off point
is 5 or more, then increase the
digit(s) before the cut-off point
by one.
3. Remove all the digits after the
cut-off
4. Fill any gaps left, after
removing the cut-off digits, with
zeroes.
64,492 might have been the exact number.
When we round off 64,492 to two
significant figures, it is 64,000.
The first non-zero digit, reading from
left to right in a number, is the first
significant figure.
e.g. In 64,492 , 6 is the first significant
figure.(sig.fig.) When we round off 64,492
to two sig. figs, that means in the answer
we should have two non zero figures.The
third figure(which is 4) is less than 5, so
we drop them to zeros.
round off 64,492 to:
(a) 1 significant figure
(b) 2 significant figures
(c) 3 significant figures
(d) 4 significant figures
(e) 5 significant figures
which is 60,000
which is 64,000
which is 64,500
which is 64,490
which is 64,492
The accuracy of the answer will depend
on the number of significant figures. The
answer will be more accurate, if it is given
to a higher number of significant figures.
64,492 is the most accurate answer and it
is given to 5 sig. figs.
*** The trailing zeros in a whole
number are not significant.There
are used to keep the other figures in
there correct places.
eg. 64000 6 and 4 are significant
not the zeros.
```