4. VAMPIRE NUMBERS
1260 is a vampire number
With 21 and 60 as fangs
Since 21 × 60 = 1260.
Others are: 1395=15 × 93
1435=41 × 35
1530=51 × 30
5. Numeric Palindrome with 1's
1x1=1
11 x 11 = 121
111 x 111 = 12321
1111 x 1111 = 1234321
11111 x 11111 = 123454321
111111 x 111111 = 12345654321
1111111 x 1111111 = 1234567654321
11111111 x 11111111 = 123456787654321
111111111 x 111111111 = 12345678987654321
6. Sequential Inputs of 9
9 x 9 = 81
99 x 99 = 9801
999 x 999 = 998001
9999 x 9999 = 99980001
99999 x 99999 = 9999800001
999999 x 999999 = 999998000001
9999999 x 9999999 = 99999980000001
99999999 x 99999999 = 9999999800000001
999999999 x 999999999 = 999999998000000001
7. Number 2519
2519 Mod 2 = 1
2519 Mod 3 = 2
2519 Mod 4 = 3
2519 Mod 5 = 4
2519 Mod 6 = 5
2519 Mod 7 = 6
2519 Mod 8 = 7
2519 Mod 9 = 8
2519 Mod 10 = 9
8. Trick
Step1: Think of a number below 10.
Step2: Double the number you have
thought.
Step3: Add 6 with the getting result.
Step4: Half the answer, that is divide it by
2.
Step5: Take away the number you have
thought from the answer, that is, subtract
the answer from the number you have
thought.
10. RULE 11
To multiply any two digit number by 11:
For this example we will use 54.
Separate the two digits in you mind
(5__4).
Notice the hole between them!
Add the 5 and the 4 together (5+4=9)
Put the resulting 9 in the hole 594. That's
it! 11 x 54=594
11. RULE 11
If the result of the addition is greater than
9
You only put the "ones" digit in the hole
and carry the "tens" digit from the
addition.
For example 11 x 57 ... 5__7 ... 5+7=12 ...
put the 2 in the hole and add the 1 from
the 12 to the 5 in to get 6 for a result of
627 ... 11 x 57 = 627
15. SNAKE EATS ITS OWN TAIL
• Choose any two digits number and for each
one reverse the digits and subtract the
smaller number from the larger.
• In each case the difference is divisible by 9
and the sum of the digits of the difference is
always 9.
16. Age Calculation Tricks:
Step1: Multiply the first number of the
age by 5.
Step2: Add 3 to the result.
Step3: Double the answer.
Step4: Add the second digit of the
number with the result.
Step5: Subtract 6 from it.
18. PUZZLE
You are at a fountain and have with you a
three gallon jug and a five gallon jug. The
jugs have no markings on the sides. How
would you be able to measure out exactly
one gallon of water?
19. SOLUTION
First, fill up the 3 gallon jug to the top, and
pour it into the 5 gallon jug.
5 - 3 = 2 free gallons left in the 5 gallon jug.
Now, fill up the 3 gallon jug again, and pour as
much as you can into the 5 gallon jug.
3 - 2 = 1 gallon of water left in the 3 gallon
jug.
Finally, pour the remaining gallon of water
from the 3 gallon jug into your 1 gallon jug.
Result = 1 gallon of water!
20. EASY SQUARING
If you want to find the square of 45.
You will first have to multiply 4 (4 +1),
that is 4 X 5, which is equal to 20
Then multiply 5 with 5, which is 25.
The answer is 2025.
Now, you can employ this method to
multiply all numbers ending with 5.
21. Bridge Crossing Puzzle:
A, B, C and D wants to cross the bridge at
night. They have only one torch light with
them. Only two can cross the bridge at a
time. They need torch light to cross the
bridge. Each of them walks at a different
speed. A needs 1 minute, B needs 2 minutes,
C needs 5 minutes and D needs 10 minutes.
A pair must walk together at the rate of the
slower person.
How these people can cross the bridge within
17 minutes?
22. Solution:
First A and B walks across the bridge, it takes
2 minutes.
A walks back with the torch light, which
takes 1 minute.
Then C and D walk on the bridge, which
takes 10 minutes.
B comes back with the torch light, it takes 2
minutes.
Finally A and B walks across the bridge,
which takes 2 minutes.
Total = 2 + 1 + 10 + 2 + 2 = 17 minutes.
