Speed Math for Kids Achieve Their Full Potential

We  divide  by  2   to  get 3,000.  We  then    multiply    the numbers in  the circles and add the result  to  3,000:

3   ×   7   =   21

3,000   +   21  =   3,021

Let’s   try one more:

Add diagonally and multiply the result by the reference number (multiply by 100 and then divide by
2):

64  +   1   =   65

65  ×   100 =   6,500

Then    we  halve   the answer.

Half    of  6,000   is  3,000.  Half    of  500 is  250.    Our subtotal    is  3,250.

Now multiply    the numbers in  the circles:

1   ×   14  =   14

Add 14  to  the subtotal    to  get 3,264.

Our problem now looks   like    this:

We  could   check   that    by  casting out the nines:

Six and 4   in  64  add up  to  10, which   added   again   gives   us  1.

Six times   1   does    give    us  6,  so  the answer  is  correct.

Test yourself

Here    are some    problems    for you to  do. See how many    you can do  in  your    head.

a)  45  ×   45  =

b)  49  ×   49  =

c)  47  ×   43  =

d)  44  ×   44  =

e)  51  ×   57  =

f)  54  ×   56  =

g)  51  ×   68  =

h)  51  ×   72  =