Welcome to the Speed
Multiply Trick
For Two Digit Numbers
Somewhere hidden
behind this page and locked with a secret password is a treasure page
bursting with FREE treasure.
To find it,
all you need to do is learn how to SPEED MULTIPLY. Then solve the password
clue problems.
When
you KNOW the password
THE
SPEED MULTIPLY TRICK: Works best with two
digit numbers.
*The following text is taken as an example from the book .
We at themathlab.com highly
recommend this book if you really want to become a mental math
whiz.
"To
multiply two 2-digit numbers without showing work, first multiply
the ones digits together, then 'cross-multiply,'
and finally multiply
the tens digits together.
Make
sure to carry whenever a product exceeds 9. As you will
see in the examples below, you must work your way from right
to left to perform this trick.
EX
1:
12 x 23 = ?
Multiply
the ones digits: 2x3=6 (ones digit answer).
Cross-multiply
and add: (1x3)+(2x2)=7 (tens-digit answer).
Multiply
the tens digits: 1x2=2 (hundreds-digit answer).
Combine:
276 (the answer).
Thought
Process Summary
EX 2:
31 x 24 = ?
Multiply the ones
digits: 1x4=4 (ones digits answer).
Cross-multiply and
add: (3x4)+(1x2)=14 (use the 4 as the tens-digit answer, and
carry the 1).
Multiply the tens
digits, and add the 1: (3x2)+1=7 (hundreds-digit answer).
Combine: 744 (the
answer).
Thought
Process Summary
*Number-Power
Note: This trick will also work on numbers with zeroes and
decimal points.
Also as you are cross-multiplying,
it is generally easier to begin with the larger product and
then add the smaller product."
Password
Clues
Use
the SPEED MULTIPLY TRICK to do the following problems in
order. When you find each answer, look in the left column
to find its corresponding letter and write this letter.
x13
x21
-----
x22
x14
-----
x32
x15
-----
x42
x42
-----
x51
x33
-----
x25
x13
-----
x44
x11
-----
x53
x34
-----
x14
x52
-----
43
x45
-----
.35
x 41
------
.23
x 55
-----
.54
x 15
-----
.21
x 51
-----
.34
x 34
-----
.12
x 45
-----
Now cross
of every o,b,r,and t. You will be left with the password.
480 = u
1,802 = k
273 = o
1,071 = o
325 = r
810 = l
728 = a
308 = f
540 = c
484 = t
1,764 = b
1,435 = b
1,156 = i
1,265 = e
1,935 = d
1,683 = n
When
you KNOW the password
To
learn even more of these mental math tricks try the book