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 doubles
 Have a friend choose a a single digit number. (No restrictions for experts.)
 Ask your friend to jot down a series of doubles (where the next term is always
double the preceding one), and tell you 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 two times the last term minus the first term.
Example:
 If the number selected is 9:
 The series jotted down is: 9, 18, 36, 72, 144.
 Two times the last term (144) minus the first (9):
2 × 144 = 288; 288  9 = 279.
 So the sum of the doubles from 9 through 144 is 279.
See the pattern? Here's one for the experts:
 The number selected is 32:
 The series jotted down is: 64, 128, 256, 512.
 Two times the last term (512) minus the first (64):
2 × 512 = 1024; 1024  32 = 1024  30  2 = 994  2 = 992.
 So the sum of the doubles from 32 through 512 is 992.
Remember to subtract in steps from left to right.
With practice you will be expert in summing series.
