Adding and subtracting decimal numbers Written methods.
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Adding and Adding and subtracting decimal subtracting decimal numbers numbers Written methods Written methods
Transcript of Adding and subtracting decimal numbers Written methods.
Adding and Adding and subtracting decimal subtracting decimal numbersnumbers
Written methodsWritten methods
AdditionAddition
ExampleExample2.15 + 1.772.15 + 1.77
2 . 1 52 . 1 5 + 1 . 7 7+ 1 . 7 7
11 2 . 1 52 . 1 5
+ 1 . 7 7+ 1 . 7 7 22
11 2 . 1 52 . 1 5
+ 1 . 7 7+ 1 . 7 7 3 . 9 23 . 9 2
5+7=125+7=12so write the 2 underneath and so write the 2 underneath and carry 1 over to the tens column carry 1 over to the tens column (this may also be written under (this may also be written under the answer)the answer)
7+1+1=97+1+1=9so write the 9 underneath so write the 9 underneath then repeat the process for the then repeat the process for the hundreds column.hundreds column.
When adding/subtracting decimals remember to line up the decimal points
SubtractionSubtraction ExampleExample
22.5 – 1.7722.5 – 1.77
2 2 . 5 02 2 . 5 0 -- 1 . 7 7 1 . 7 7
4 14 1
2 2 . 5 02 2 . 5 0 -- 1 . 7 7 1 . 7 7
33
1 141 14 11 2 2 . 5 02 2 . 5 0
-- 1 . 7 7 1 . 7 7 . 7 3. 7 3
1 141 14 11 2 2 . 5 0 2 2 . 5 0
-- 1 . 7 7 1 . 7 7 2 0 . 7 32 0 . 7 3
4 - 7= a negative number4 - 7= a negative numberso borrow one from the units column. so borrow one from the units column. Now we have 14 – 7 = 7.Now we have 14 – 7 = 7.
Make sure that both numbers have the same amount of digits after the decimal point by adding a zero.
0 – 7 = a negative number so 0 – 7 = a negative number so borrow one from the tenths column. borrow one from the tenths column. Now we have Now we have 10 – 7 = 3.10 – 7 = 3.
Now complete the sum,
1 – 1 = 0,
2 – 0 = 2.
