Decimals Flashcards
How to convert decimals to fractions
Count how many decimal places there are in the decimal number.
3 DP = 1000’s
2DP = 100’s
1DP = 10’s
- For example 0.084 has 3 decimal places
- It is 84/1000
- CANCEL CANCEL CANCEL down your fraction to lowest possible terms
- 84/1000
- 48/500
- 21/250
Answer = 21/250
What is a significant figure?
Digits that have a value attached to them.
They start at the first non zero number (ignore zeros at the front but not the ones in between)
Ascending
small to large
Descending
large to small
Number of zeros after decimal point - how does this help convert fraction to decimal
- 5 = 5/10
- 06 = 6/100
- 007 = 7/1000
number of places after the decimal point is the number of zeros on the denominator
Adding and subtracting decimals
Keep the decimal place and add as normal
Line them up in column sub and add
Multiply by 10, move decimal point?
one place
Multiply by 100, move decimal point
two places
Multiply by 1000, move decimal point
three places
Multiply decimal by whole number - procedure
ESTIMATE first
long multiplication of decimals
Multiply decimal by decimal number
ESTIMATE first
Do multiplication
Count DP in both numbers
Add in to answer
Divide decimals by whole number
ESTIMATE
Normal division
DP carries down to same place
Round 53,879 to 1 significant figure, then 2 significant figures.
5|3879 to 1 significant figure is 50,000
53|879 to 2 significant figures is 54,000
Notice that the number of significant figures in the question is the maximum number of non-zero digits in your answer.
Round 0.005089 to 1 significant figure, then 2 significant figures.
- 005|089 to 1 significant figure is 0.005
0. 0050|89 to 2 significant figures is 0.0051
