Divisibility Rule
Divisibility Rule
- What is the divisibility by 2 Rule?
- Even numbers are multiples of 2. A number is even if ends in 0,2,4,6, or 8.
- What is the divisibility by 3 rule?
- A number is divisible by 3 if the sum of its digits is divisible by 3.
- 372, for instance, is divisible by 3 since sum of its digits (3+7+2) is 12. And 12 is divisible by 3.
- What is the divisibility by 4 rule?
- A number is divisible by 4 if the number\'s last two digits are divisible by 4
- 9,312, for instance, is divisible by 4 since its last 2 digits are 12. And 12 is divisible by 4.
- What is the divisibility by 5 rule?
- A number is divisible by 5 if its last digit is a 0 or 5.
- What is the divisibility by 6 rule?
- Since 6 is a multiple of 2 and 3, the rules for divisibility by 6 are a combination of the rule for 2 and the rule for 3.
- Divisibility by 8 Rule
- A number passes the test for 8 if the last three digits form a number is divisible 8.
- Divisibility by 9 Rule
- A number is divisible by 9 if the sum of the digits are evenly divisible 9.
- Divisibility by 10 Rule
- A number passes the test for 10 if its final digit is 0
Important Maths Formulas .
(a ± b) 2 = a 2 ± 2ab + b 2 .
(a + b + c) 2 = a 2 + b 2 + c 2 + 2(ab + bc + ca).
(a + b + c + d) 2 = a 2 + b 2 + c 2 + d 2 + 2(ab + ac + ad + bc + bd + cd) .
Geometry formulas .
Perimeter ( ചുറ്റളവ് ) .
Perimeter of a square: P=4a.
a: length of one side.
Perimeter of a rectangle: P=2(l+w).
l: length.
w: width.
Perimeter of a triangle: P=a+b+c.
a, b, and c: lengths of the 3 sides.
Area ( വിസ്തീര്ണ്ണം ) .
LINE_FE...
N = the number of terms .
S = the sum of the numbers in the set.
Average = S/N .
For example.
The marks of a student in five subjects are 96, 94, 92, 87, and 81, then what is the average score of the student?.
N = 5.
S = 96 + 94 + 92 + 87 + 81 = 450.
A = 450/5 = 90.
Another type questions .
1). There are 36 boys and 44 girls in a class. The average score of boys is 40 and girls are 35. Then what will be the average mark? .
Total mark of 36 boys = 36 x 40 = 1440.
Total mark of 44 girls = 35 x 44 = 1540.
Total mark of 80 Students = 1440 + 1540 = 2980 .
Average mark of the class = (2980 / 80).
...
P - Principal, the sum of money lent or borrowed. .
R - Rate of interest: Annual interest, often expressed as a percentage. .
T - Time period for which the money is lent or borrowed. .
Simple Interest = Principal * Time * Rate of interest / 100 .
SI = 4000× 8% × 4 = 4000× 0.08 × 4.
= 1280. .
In compound interest , the principal amount with interest after the first time period becomes the part of principal for the next time period.
CI = [P (1 + R/100)^T] – P .
Total amount = [P (1 + R/100)^T] .
If time period is half-yearly, .
Amount = P[1 + (R/2)/100]^2T .
If time period is quarterly, .
Amount = P[1 + (R/4)/100...
