Speedy Math 2 – Transformation in Addition and Subtraction

Addition of two single digit numbers is easy. It becomes more difficult when the numbers contain more digits. In these cases, changing the number(s) first to an equal form can make the calculation much easier.

For example, 198 + 277
Step 1: 198 = 200 – 2
Step 2: 200 + 277 = 477 (or 277 – 2 = 275)
Step 3: 477 - 2 = 475 (or 200 + 275 = 475)

Another example, 673 – 395
Step 1: 395 = 400 – 5
Step 2: 673 – 5 = 668
Step 3: 400 + 668 = 1068

Speedy Math 1 – Addition of Series of Numbers

A lot of girls find math difficult. The more they think so, the less they want to work on it. Fortunately, there are many regulations and “tricks” in math. As soon as they learn the tricks, the math becomes much easier and more enjoyable. For some problems, it’s almost impossible to solve in a short time period without knowing the tricks. Addition of a regular series of numbers is a classic example.

For example, what is the sum of all the numbers from 1 to 20?
It may take a while to add the numbers from 1 to 20 one by one. But it is much easier if the following steps are followed:
Step 1: Find the number of numbers in the series = (last number – first number + 1) =(20 - 1 + 1)= 20
Step 2: Calculate the average of the first and the last number of the series = (20 + 1)/2 = 21/2 = 10.5
Step 4: Calculate the final result = average x number = 10.5 x 20 = 210

This trick can be extrapolated to much more complicated problems. In the exam situations, it’s is practically impossible to solve the problem without knowing the above trick.

For example, what is the sum of all the numbers from 131 to 1997?
Knowing above trick, the problem can be quickly solved as:
(1997 - 131 + 1) = 1867
(131 + 1991)/2 = 1064
Final answer = 1064 x 1867 = 1986488

After some time, you may forget the exact steps described above. In that case, just try the simplest series: 1 + 2 + 3
(3 - 1 + 1) = 3
(3 + 1)/2 = 2
2 x 3 = 6

Beautiful Math

Math can be difficult, but it can be fun and beautiful too. Here are some examples:

111,111,111 x 111,111,111 = 12,345,678,987,654,321


3 x 37 = 111
6 x 37 = 222
9 x 37 = 333
12 x 37 = 444
15 x 37 = 555
18 x 37 = 666
21 x 37 = 777
24 x 37 = 888
27 x 37 = 999


0x 9 + 1 = 1
1 x 9 + 2 = 11
12 x 9 + 3 = 111
123 x 9 + 4 = 1111
1234 x 9 + 5 = 11111
12345 x 9 + 6 = 111111
123456 x 9 + 7 = 1111111
1234567 x 9 + 8 = 11111111
12345678 x 9 + 9 = 111111111
123456789 x 9+10 = 1111111111


1 x 8 + 1 = 9
12 x 8 + 2 = 98
123 x 8 + 3 = 987
1234 x 8 + 4 = 9876
12345 x 8 + 5 = 98765
123456 x 8 + 6 = 987654
1234567 x 8 + 7 = 9876543
12345678 x 8 + 8 = 98765432
123456789 x 8 + 9 = 987654321


0x 9 + 8 = 8
9 x 9 + 7 = 88
98 x 9 + 6 = 888
987 x 9 + 5 = 8888
9876 x 9 + 4 = 88888
98765 x 9 + 3 = 888888
987654 x 9 + 2 = 8888888
9876543 x 9 + 1 = 88888888
98765432 x 9 + 0 = 888888888
987654321 x 9 - 1 = 8888888888
9876543210 x 9 - 2 = 88888888888