Squaring Numbers
Multiplying Numbers
Dividing Numbers
Adding Numbers
 even numbers 2 through selected 2digit evens
 digits of square of repeating ones
 consecutive odds
 consecutive between 2 numbers
 sequence from 1 to selected 2digit number
 sequence from 1 to selected 1digit number and back
 sequences in the 10's
 sequences in the 20's
 sequences in the 30's
 sequences in the 40's
 sequences in the 50's
 sequences in the 60's
 sequences in the 70's
 sequences in the 80's
 series of doubles
 series of quadruples
 series of 10 numbers
Subtracting Numbers
 1's repeating, divide by 9, subtract 21
 8's repeating, divide by 9, subtract 10
 squares of two numbers
 reversing/adding/subtracting 3digit numbers
Percents
 finding 2.5 percent
 finding 5 percent
 finding 15 percent
 finding 20 percent
 finding 25 percent
 finding 33 1/3 percent
 finding 40 percent
 finding 45 percent
 finding 55 percent
 finding 60 percent
 finding 70 percent
 finding 75 percent
Calculation
Practice Exercises
Full List

Adding
a series of quadruples
 Have a friend choose a single digit number. (No restrictions for experts.)
 Ask your friend to jot down a series of quadruples (where the next term is always
four times the preceding one), and tell you only the last term.
 Ask your friend to add up all these terms.
 You will give the answer before he or she can finish: The sum of all the terms
of this series will be four times the last term minus the first term, divided
by 3.
Example:
 If the number selected is 5:
 The series jotted down is: 5, 20, 80, 320, 1280.
 Four times the last term (1280) minus the first (5):
4000 + 800 + 320  5 = 5120  5 = 5115
Divide by 3: 5115/3 = 1705
 So the sum of the quadruples from 5 through 1280 is 1705.
See the pattern? Here's one for the experts:
 The number selected is 32:
 The series jotted down is: 32, 128, 512, 2048.
 Four times the last term (2048) minus the first (32):
8000 + 160 + 32  32 = 8,160
Divide by 3: 8160/3 = 2720.
 So the sum of the quadruples from 32 through 2048 is 2720.
Practice multiplying from left to right and dividing by 3. With practice you will
be an expert quad adder.
