Short-Cut Math, Gerard Kelly
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Gerard Kelly

Short-Cut Math

manzoorarshad
manzoorarshadje citiraoпре 3 године
You can sometimes avoid borrowing if you subtract by pairs of digits instead of by individual digits.
manzoorarshad
manzoorarshadje citiraoпре 3 године
Instead of adding, you may find it easier to subtract the same amount from both numbers. Again, this will not change the difference between the numbers.
manzoorarshad
manzoorarshadje citiraoпре 3 године
You can simplify subtraction by changing the number to be subtracted into a number ending in zero. This can be done with an easy addition or subtraction.
manzoorarshad
manzoorarshadje citiraoпре 3 године
Or you can add the same amount to both numbers, like this:
manzoorarshad
manzoorarshadje citiraoпре 3 године
Thinking of Numbers as “Dollars” and “Cents”
manzoorarshad
manzoorarshadje citiraoпре 3 године
If numbers contain two or more digits, splitting the numbers into smaller parts can make them easier to add.
manzoorarshad
manzoorarshadje citiraoпре 3 године
In a long column, you can add the numbers by groups to get sub-totals and then add the sub-totals to get the sum total
manzoorarshad
manzoorarshadje citiraoпре 3 године
If a number is repeated, especially if repeated often, you can use multiplication to speed up your addition
manzoorarshad
manzoorarshadje citiraoпре 3 године
you learn to “see” these groups as a single number, you will be able to add faster and easier.
manzoorarshad
manzoorarshadje citiraoпре 3 године
sum of two digits at once, without stopping to count
manzoorarshad
manzoorarshadje citiraoпре 3 године
you would not say “9 and 4 make 13, and 7 makes 20.” Instead, you “think” the addition without the words:
manzoorarshad
manzoorarshadje citiraoпре 3 године
You can also simplify addition by changing difficult numbers into easier ones
manzoorarshad
manzoorarshadje citiraoпре 3 године
Numbers may be added in any order
manzoorarshad
manzoorarshadje citiraoпре 3 године
Adding by 10 is easy, so look for combinations that add to 10.
manzoorarshad
manzoorarshadje citiraoпре 3 године
By adding an amount 10 one number and subtracting an equal amount from a second number, the sum of the two numbers remains the same.
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