Squaring Numbers
Multiplying Numbers
 same 1st digit
 same 1st digit, sum 10
 same 2nd digit
 3 digits, middle 0
 3 digits, middle 1
 3 digits, middle 2
 3 digits, middle 3
 3 digits, middle 4
 3 digits, middle 5
 difference of 1
 difference of 2
 difference of 3
 difference of 4
 difference of 6
 difference of 8
 difference of 10
 2 digits by 1 1/25
 2 digits by 1 1/16
 2 digits by 1 1/15
 2 digits by 1.1
 2 digits by 1 1/9
 2 digits by 1 1/8
 2 digits by 1 1/7
 2 digits by 1 1/6
 2 digits by 1 1/5
 2 digits by 1 2/9
 2 digits by 1 1/4
 2 digits by 1 2/7
 2 digits by 1.3
 2 digits by 1 1/3
 2 digits by 1 3/8
 2 digits by 1 2/5
 2 digits by 1 3/7
 2 digits by 1 1/2
 2 digits by 1 4/7
 2 digits by 1 3/5
 2 digits by 1.6
 2,3 digits by 1 2/3
 2 digits by 1.7
 2 digits by 1 5/7
 2 digits by 1 3/4
 2 digits by 1 4/5
 2 digits by 1 5/6
 2 digits by 1 6/7
 2 digits by 1.9
 2 digits by 2.1
 2 digits by 2 1/9
 2 digits by 2 1/7
 2 digits by 2 1/5
 2 digits by 2 2/9
 2 digits by 2 1/4
 2 digits by 2.3
 2 digits by 2 1/3
 2 digits by 2 3/8
 2 digits by 2 2/5
 2 digits by 2.4
 2 digits by 2 4/9
 2, 3 digits by 2 1/2
 2 digits by 2 4/7
 2 digits by 2.6
 2 digits by 2 5/8
 2 digits by 2 2/3
 2 digits by 2.7
 2 digits by 2 5/7
 2 digits by 2 3/4
 2 digits by 2.8
 2 digits by 2 7/9
 2 digits by 2 6/7
 2 digits by 2.9
 2 digits by 3.1
 2 digits by 3 1/8
 2 digits by 3 1/7
 2 digits by 3 1/6
 2 digits by 3.2
 2 digits by 3 2/9
 2 digits by 3 1/4
 2 digits by 3 1/3
 2 digits by 3.4
 2 digits by 3 3/7
 2 digits by 3 4/9
 2 digits by 3 1/2
 2 digits by 3.6
 2 digits by 3 4/7
 2 digits by 3 5/8
 2 digits by 3 2/3
 2 digits by 3.7
 2 digits by 3 5/7
 2 digits by 3 3/4
 2 digits by 3 4/5
 2 digits by 3 6/7
 2 digits by 3 7/8
 2 digits by 3.9
 2 digits by 4.1
 2 digits by 4 1/4
 2 digits by 4 1/7
 2 digits by 4 1/6
 2 digits by 4 1/5
 2 digits by 4 2/7
 2 digits by 4 1/3
 2 digits by 4.3
 2 digits by 4.4
 2 digits by 4 3/7
 2 digits by 4 4/9
 2 digits by 4 1/2
 2 digits by 4 5/9
 2 digits by 4.6
 2 digits by 4 2/3
 2 digits by 4.7
 2 digits by 4 3/4
 2 digits by 4 4/5
 2 digits by 4 5/6
 2 digits by 4 7/8
 2 digits by 4.9
 2 digits by 5.1
 2 digits by 5 1/8
 2 digits by 5 1/6
 2 digits by 5.2
 2 digits by 5 1/4
 2 digits by 5.3
 2 digits by 5 4/9
 2 digits by 5 1/2
 2 digits by 5 5/9
 2 digits by 5.6
 2 digits by 5.7
 2 digits by 5 4/7
 2 digits by 5 5/7
 2 digits by 5 4/5
 2 digits by 5 6/7
 2 digits by 5.9
 2 digits by 6.1
 2 digits by 6 1/8
 2 digits by 6 1/5
 2 digits by 6 1/4
 2 digits by 6.3
 2 digits by 6 1/3
 2 digits by 6 3/8
 2 digits by 6.4
 2 digits by 6 4/9
 2 digits by 6 1/2
 2 digits by 6 5/9
 2 digits by 6.6
 2 digits by 6 2/3
 2 digits by 6 7/9
 2 digits by 6 5/6
 2 digits by 6.8
 2 digits by 6 6/7
 2 digits by 6 8/9
 2 digits by 6.9
 2 digits by 7.1
 2 digits by 7 1/7
 2 digits by 7.2
 2 digits by 7 1/4
 2 digits by 7.3
 2 digits by 7 2/7
 2 digits by 7.4
 2 digits by 7 1/2
 2 digits by 7 3/5
 2 digits by 7.6
 2 digits by 7.7
 2 digits by 7 3/4
 2 digits by 7 4/5
 2 digits by 8.1
 2 digits by 8 1/6
 2 digits by 8.2
 2 digits by 8 2/7
 2 digits by 8.3
 2 digits by 8 1/3
 2 digits by 8 3/7
 2 digits by 8 4/7
 2 digits by 8 1/2
 2 digits by 8.6
 2 digits by 8 5/8
 2 digits by 8 2/3
 2 digits by 8 5/7
 2 digits by 8 7/9
 2 digits by 8.8
 2 digits by 8 7/8
 2 digits by 8 8/9
 2 digits by 8.9
 2 digits by 9.1
 2 digits by 9.2
 2 digits by 9.3
 2 digits by 9 1/3
 2 digits by 9.4
 2 digits by 9 1/2 (four steps)
 2 digits by 9 1/2 (two steps)
 2 digits by 9.6
 2 digits by 9 2/3
 2 digits by 9 5/7
 2 digits by 9.7
 2 digits by 9 3/4
 2 digits by 9 7/9
 2 digits by 9 4/5
 2 digits by 9 5/6
 2 digits by 9 6/7
 2 digits by 9 7/8
 2 digits by 9 8/9
 2 digits by 10.1
 2 digits by 10.4
 2 digits by 10.6
 2 digits by 10.7
 2 digits by 10 1/2
 2 digits by 11 1/2
 2 digits by 12 1/2
 2 digits by 15
 2,3 digits by 16 2/3
 2 digits by 18
 2 digits by 19 1/2
 2 digits by 20 1/2
 2 digits by 21
 2 digits by 22
 2 digits by 23
 2 digits by 24
 2,3 digits by 25
 2 digits by 26
 2 digits by 27
 2 digits by 28
 2 digits by 29
 2 digits by 29 1/2
 2 digits by 30 1/2
 2 digits by 31
 2 digits by 32
 2 digits by 33
 2 digits by 33 1/3
 2 digits by 34
 2 digits by 35
 2 digits by 36
 2 digits by 37
 2 digits by 37 1/2
 2 digits by 38
 2 digits by 39
 2 digits by 39 1/2
 2 digits by 40 1/2
 2 digits by 42
 2 digits by 43
 2 digits by 44
 2 digits by 45
 2 digits by 46
 2 digits by 47
 2 digits by 48
 2 digits by 49 (a)
 2 digits by 49 (b)
 2 digits by 49 1/2
 2 digits by 50 1/2
 2 digits by 51
 2 digits by 52
 2 digits by 53
 2 digits by 54
 2 digits by 55 (a)
 2 digits by 55 (b)
 2 digits by 56
 2 digits by 57
 2 digits by 58
 2 digits by 59
 2 digits by 59 1/2
 2 digits by 60 1/2
 2 digits by 61
 2 digits by 62
 2 digits by 63
 2 digits by 64
 2 digits by 65
 2 digits by 66
 2 digits by 67
 2 digits by 68
 2 digits by 69
 2 digits by 69 1/2
 2 digits by 70 1/2
 2 digits by 71
 2 digits by 72
 2 digits by 73
 2 digits by 74
 2,3 digits by 75
 2 digits by 76
 2 digits by 77
 2 digits by 78
 2 digits by 79
 2 digits by 79 1/2
 2 digits by 80 1/2
 2 digits by 81
 2 digits by 82
 2 digits by 83
 2 digits by 84
 2 digits by 85
 2 digits by 86
 2 digits by 87
 2 digits by 88
 2 digits by 89
 2 digits by 89 1/2
 2 digits by 90 1/2
 2 digits by 91
 2 digits by 92
 2 digits by 93
 2 digits by 94
 2 digits by 95
 2 digits by 97
 2 digits by 98
 2 digits by 99
 3 digits by 99
 2,3 digits by 101
 2 digits by 102 + 11
 2 digits by 103 + 12
 2 digits by 125
 3 digits by 143
 2 digits by 166 2/3
 2 digits by 198
 2 digits by 201 + 11
 2 digits by 202 + 11
 2 digits by 250
 2 digits by 297
 2 digits by 375
 2 digits by 396
 2 digits by 495
 2 digits by 594
 2 digits by 625
 2 digits by 693
 2 digits by 792
 2 digits by 875
 2 digits by 891
 2 digits by 999
 2,3 digits by 1001 + 21,201
 24 digits by 1000, + 21, 201, 2001
 25 digits by 100001
 1 rep. by 9 rep.
 1 rep. by 12 rep.
 1 rep. by 13 rep.
 1 rep. by 14 rep.
 1 rep. by 15 rep.
 1 rep. by 16 rep.
 1 rep. by 17 rep.
 1 rep. by 18 rep.
 1 rep. by 19 rep.
 1 rep. by 21
 1 rep. by 22
 1 rep. by 23
 1 rep. by 24
 1 rep. by 25
 1 rep. by 26
 1 rep. by 27
 1 rep. by 29
 1 rep. by 33
 1 rep. by 41
 1 rep. by 44
 1 rep. by 45
 1 rep. by 55
 1 rep. by 66
 1 rep. by 77
 1 rep. by 88
 1 rep. by 99
 1 rep. by 222
 1 rep. by 333
 2 rep. by 5 rep.
 2 rep. by 9 rep.
 2 rep. by 12
 2 rep. by 13
 2 rep. by 14
 2 rep. by 15
 2 rep. by 16
 2 rep. by 17
 2 rep. by 22
 2 rep. by 24
 2 rep. by 28
 2 rep. by 29
 2 rep. by 33
 2 rep. by 44
 2 rep. by 45
 2 rep. by 55
 2 rep. by 66
 2 rep. by 77
 2 rep. by 88
 2 rep. by 99
 3 rep. by 6 rep.
 3 rep. by 9 rep.
 3 rep. by 13
 3 rep. by 14
 3 rep. by 15
 3 rep. by 22
 3 rep. by 23
 3 rep. by 24
 3 rep. by 35
 3 rep. by 55
 3 rep. by 66
 3 rep. by 77
 3 rep. by 88
 3 rep. by 99
 4 rep. by 13
 4 rep. by 14
 4 rep. by 15
 4 rep. by 17
 4 rep. by 22
 4 rep. by 24
 4 rep. by 28
 4 rep. by 31
 4 rep. by 36
 4 rep. by 42
 4 rep. by 44
 4 rep. by 55
 4 rep. by 66
 4 rep. by 88
 4 rep. by 99
 4 rep. by 3 rep.
 4 rep. by 5 rep.
 4 rep. by 9 rep.
 5 rep. by 15
 5 rep. by 25
 5 rep. by 28
 5 rep. by 33
 5 rep. by 55
 5 rep. by 66
 5 rep. by 77
 5 rep. by 88
 5 rep. by 99
 5 rep. by 9 rep.
 6 rep. by 9 rep.
 6 rep. by 12
 6 rep. by 15
 6 rep. by 16
 6 rep. by 22
 6 rep. by 31
 6 rep. by 32
 6 rep. by 33
 6 rep. by 43
 6 rep. by 55
 6 rep. by 66
 6 rep. by 77
 6 rep. by 88
 6 rep. by 444
 6 rep. by 888
 7 rep. by 9 rep.
 7 rep. by 15
 7 rep. by 17
 7 rep. by 32
 7 rep. by 33
 7 rep. by 42
 7 rep. by 44
 7 rep. by 55
 7 rep. by 66
 7 rep. by 77
 7 rep. by 88
 7 rep. by 99
 8 rep. by 9 rep.
 8 rep. by 22
 8 rep. by 23
 8 rep. by 24
 8 rep. by 29
 8 rep. by 36
 8 rep. by 44
 8 rep. by 55
 8 rep. by 66
 8 rep. by 88
 9 rep. by 14
 9 rep. by 22
 9 rep. by 25
 9 rep. by 27
 9 rep. by 33
 9 rep. by 44
 9 rep. by 55
 9 rep. by 77
 9 rep. by 88
 9 rep. by 99
 3 repeating by 2, /37
 3 repeating by 5, /37
 9 rep. by 3, /12345679
 multidigits by 8 + last digit
 by 8, add number,  20
 integer + 1/2 times, + 1
 sum,difference of 2,1 digits
 two mixed numbers
 two mixed numbers,fractions
 4 digits by 99
 4 digits by 137, then 73; 1200
 5 digits by 9091, then 11; 1200
Dividing Numbers
Adding Numbers
Subtracting Numbers
Finding Percents
Calculation
Practice Exercises
Full List

Multiplying two selected 3digit numbers
(middle
digit 2)
 Select a 3digit number with a middle digit of 2.
 Choose a multiplier with the same first two digits, whose third digit sums to
10 with the third digit of the first 3digit number.
 The last two digits will be the product of the third digits: _ _ _ _X X.
 The third digit from the right will be 6: _ _ 6 _ _.
 The next digit to the left will be 5 times the first digit of the number (keep
carry): _ _ X _ _ _.
 The first digits will be the square of the first digit plus the carry: X X _
_ _ _.
As you determine the digits in the answer from right to left, repeat them to yourself
at each step until you have the whole answer.
Example:
 If the first number is 622, choose 628 as the second number (same
first digits, third digits add to 10).
 2 × 8 = 16 (multiply the third digits)  last two digits:
_ _ _ _ 1 6.
 The third digit from the right is 6: _ _ 6 _ _ _.
 5 × 6 = 30 (the next digit to the left is 5 times the first digit (keep carry
3): _ _ 0 _ _ _ .
 6 × 6 = 36; 64 + 3 = 39 ( the first digits are the square of the first digit
plus the carry: 3 9 _ _ _ _.
 So 622 × 628 = 390616.
See the pattern?
 If the first number is 221, choose 229 as the second number (same
first digits, third digits add to 10).
 1 × 9 = 9 (multiply the third digits)  last two digits:
_ _ _ 0 9.
 The third digit from the right is 6: _ _ 6 _ _.
 5 × 2 = 10 (the next digit to the left is 5 times the first digit (keep carry
1): _ 0 _ _ _ .
 2 × 2 = 4; 4 + 1 = 5 ( the first digits are the square of the first digit plus
the carry: 5 _ _ _ _.
 So 221 × 229 = 50609.
