Foreward: Math-Is There a Faster Way?
Multiplying 11 times any number
7421×11
Multiplying 12 times any number
123×12=
Multiplying together two-digit numbers having 5 as the tens digit
51×58=
21×81=
12×18=
Multiplying together two-digit numbers having the ones digits the same
21×41=
Multiplying together two-digit numbers having the tens digits the same
23×21=
Multiplying together two-digit numbers that have a convenient square between them
29×31=
Multiplying together numbers just below 100
96×98=
Multiplying a two-digit number ending in 1 times another two-digit number ending in 1
21×51=
Multiplying two two-digit numbers that end in 5 and have a difference of 10
75×85=
Multiplying together three-digit numbers whose middle digits are 0
205×406=
Multiplying together numbers ending in 0
6000×1200=
Multiplying together two-digit numbers ending in 5
15×65=
Multiplying together numbers near 50
46×48= 53×56=
Multiplying numbers near 50 with those near near 100
94×48=
Squaring two-digit numbers ending with 5
(65)(65)=
Squaring two-digit numbers having 5 as the tens digit
(53)(53)=
Squaring three-digit numbers having 0 in the tens place
(506)(506)=
(94)(94)= (107)(107)=
Simplifying multiplication by halving and doubling.
12×15=
Squaring a number that is seen to be the midpoint between two numbers easier to multiply
(29)(29)=
24×62=
2+22+222+2222+22222=
Obtaining the sum of successive odd digits
1+3+5+7=
Obtaining the number of possible combinations of a set of elements
[A,B,C,D] combinations
What is happening when you divide fractions-an explanation
Chisanbop is useful in recalling numbers in the midst of calculation