Show numerical properties of
25
twenty five
Make blocks of 5
1 tally mark = |
2 tally marks = ||
3 tally marks = |||
4 tally marks = ||||
5 tally marks = | | | |
5 = | | | |
10 = | | | |
15 = | | | |
20 = | | | |
25 = | | | |
| | | | | | | | | | | | | | | | | | | |
Define an ordinal number
A position in a list
25th
Calculate the digit sum of 25
Calculate the reduced digit sum of 25
Digit Sum → 2 + 5 = 7
Since our digit sum ≤ 9:
we have our reduced digit sum
Digit Sum → 2 + 5 = 7
Calculate the digit product of 25
Digit Product = Value when you multiply
all the digits of a number together.
We multiply the 2 digits of 25 together
Digit product of 25 = 2 * 5
Digit product of 25 = 10
Opposite of 25 = -(25)
Opposite of = -25
25! = 25 x 24 x 23 x 22 x 21 x 20 x 19 x 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
25! = 1.5511210043331E+25
Place value describes each digit
2 is our tens digit
This means we have 2 sets of tens
5 is our ones digit
This means we have 5 sets of ones
2 is our tens digit
5 is our ones digit
When e^{y} = x and e = 2.718281828459
We have Ln(x) = log_{e}(x) = y
Ln(25) = log_{e}(25) = 3.2188758248682
Is 25 divisible by:
2,3,4,5,6,7,8,9,10,11
Last digit ends in 0,2,4,6,8
The last digit of 25 is 5
Since 5 is not equal to 0,2,4,6,8:
then 25 is not divisible by 2
Sum of the digits is divisible by 3
The sum of the digits for 25 is 2 + 5 = 7
Since 7 is not divisible by 3:
Then 25 is not divisible by 3
Take the last two digits
Are they divisible by 4?
The last 2 digits of 25 are 25
Since 25 is not divisible by 4:
Then 25 is not divisible by 4
Number ends with a 0 or 5
The last digit of 25 is 5
Since 5 is equal to 0 or 5:
Then 25 is divisible by 5
Divisible by both 2 and 3
Since 25 is not divisible by 2 and 3:
Then 25 is not divisible by 6
Multiply each respective digit by 1,3,2,6,4,5
Work backwards
Repeat as necessary
5(1) + 2(3) = 12
Since 12 is not divisible by 7:
Then 25 is not divisible by 7
Take the last three digits
Are they divisible by 8
The last 2 digits of 25 are 25
Since 25 is not divisible by 8:
Then 25 is not divisible by 8
Sum of digits divisible by 9
The sum of the digits for 25 is 2 + 5 = 7
Since 7 is not divisible by 9:
Then 25 is not divisible by 9
Ends with a 0
The last digit of 25 is 5
Since 5 is not equal to 0:
Then 25 is not divisible by 10
Σ odd digits - Σ even digits = 0
or 25 is a multiple of 11
25
2
Odd Sum = 2
25
5
Even Sum = 5
Δ = Odd Sum - Even Sum
Δ = 2 - 5
Δ = -3
Because Δ / 11 = 2.2727272727273:
Then 25 is NOT divisible by 11
25 is divisible by
(5)