Page 107 - Math Smart - 7

Decimals
Place-value table

1 2 9 4 • 7 6 5

Multiplying by 10, 100 or 1000
'1'" ; • !-• L'Lk
X 10 0 • 2 3 X 100 0 • 2 3 --6 X 1000 0 • 2 ^6
2 • 3 6* 2 3 • 2 3 6m
When you multiply by 10, When you multiply by 100, each When you multiply by 1000, each
each digit moves one place digit moves two places to the left. digit moves three places to the left.
to the left. This makes the This makes the number greater. This makes the number greater.
number greater.
Dividing by 10, 100 or 1000

^10 1 8 2 • 1 8-^3 2 • ■rIOOO 1 8_ ^3 2 •
1 8 ^3 • 2 o o 1 *^8 • 3 2 1 • '8 3 2
When you divide by 10, each digit When you divide by 100, each digit When you divide by 1000, each digit
moves one place to the right. This moves two places to the right. This moves three places to the right. This
makes the number smaller. makes the number smaller. makes the number smaller.

Ordering decimals

Ascending order Descending order
The decimals arranged 6 • 4 5 The decimals arranged in
in ascending order from 5 • 5 2 descending order from greatest
smallest to greatest is: 6 • 4 8 to smallest is:
5.52 6.45 6.48 6.48 6.45 5.52

Estimating and
Rounding decimals approximating

round down round up ak&calcuiations

obtain an answer that makes sense
in the word problem and Is close
enough to the actual answer
19 19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8 19.9 20
check whether your answer is
reasonable