Speed Math for Kids Achieve Their Full Potential

74 × 10 = 740

1 × 7 = 7

740 + 7 = 747

Easy.   Now let’s   use 10  and 80  as  reference   numbers.

There was not much difference in this case, but if you have a large number to subtract you may find it
easier to choose your reference numbers so that you end your calculation with an addition.
You could also solve this problem using 10 and 100 as reference numbers. Let’s try it.

There are many ways you can use these methods to solve problems. It is not a matter of which
method is right but which method is easiest, depending on the particular problem you are trying to
solve.

Test yourself

Try these   problems    by  yourself:

a)  9   ×   68  =

b)  8   ×   79  =

c)  94  ×   192 =

d)  98  ×   168 =

Write   them    down    and calculate   the answers,    and then    see if  you can do  them    all in  your    head.   With    practice    it  becomes easy.   Here

are the answers:

a)  612

b)  632

c)  18,048

d)  16,464

Easy multiplication by 9

It is easy to use this method to multiply any number from 1 to 1,000 by 9.
Let’s try an example:
76 × 9 =
We use 10 as our reference for 9 and 80 as our reference for 76. We can rewrite the problem like this:

We subtract 8 from 76 (76 − 10 = 66, plus 2 is 68). Multiply 68 by the base reference, 10, which
equals 680. Now multiply the numbers in the original circles, and add the result to 680.